How to tip Taxi drivers:

CountryTipping guidelines for Taxis, Drivers and Mobility as a service providers
Afghanistan not common
Albania not common, but appreciated
Algeria if prize is negotiated, not common. 
If the driver is helpful 5-10 Dinar
American Samoa not recquired
Andorra Round up the bill
Angola not common, but appreciated
Anguilla 10 % to 15 %
Antigua & Barbuda 10 % to 15 %
Argentina Rounding up the change is appreciated
Armenia 10-20 % (3-5 $)
Aruba Prices are fixed, but  tipps are appreciated
Australia 10 % or even small change can be sufficient
Austria Round up to the nearest euro or up to 10 percent of the final fare for good service
Azerbaijan 8-20 % or around 3 to 5 $
Bahamas, The For short distances round up to the next dollar, longer distances 1-2 $ is acceptable, more can be appreciated
Bahrain If a taxi is uses the meter, a 10% tip would be a good idea (without a meter tourists are often being overcharged)
Bangladesh not common
Barbados Rounding up the change is appreciated,  but always try to agree on the fare first
Belarus if the taxi is not overcharged, a ruble is ok
Belgium not common, but a giving the change is appreciated, especially when helping with the lugagge
Belize Not common to tip, important to negotiate a price first, especially long distance
Benin you should round up the fare.
Bermuda Tipping a taxi driver is common. You should aim to tip about 10% of the fare.
Bhutan Only the fare, no custom of tipping taxi drivers.
Bolivia No tip expected unless you hire them for a full day then +10% to the fare (5-10$ is sufficient)
Bosnia & Herzegovina Rounding up the change is appreciated
Botswana 10%
Brazil Taxi drivers are usually not tipped, but it’s customary to round up the fare to the next Real.
British Virgin Is. Round up the fare
Brunei Taxi drivers do not expect tips 
Bulgaria Round up the fare
Burkina Faso Tipping taxi drivers in Burkina Faso is expected, you should aim to tip 10-15%
Burma Round up the fare
Burundi Tipping taxi drivers in Burundi is not expected, but if it was a pleasant ride then you should round up.
Cambodia For tuk tuk and moto drivers, tips again are not expected – especially seeing as you, as a foreigner, are probably already being drastically over-charged. Of course, a couple of leftover riels are always appreciated.
Cameroon Tips are not expected, but add one for good service.
Canada 2-5$
Cape Verde Round up the fare
Cayman Islands 10-15 %
Central African Rep. 10-15 %
Chad Round up the fare
Chile Generally not expected, but can let them keep the change or round up to the nearest 500.
China Tip is not required. If the driver helps you with heavy luggage or makes a special effort then  a small tip may be well-received. 
Colombia Tipping isn’t customary, but you can round up the fare (30-50 cents = 1000 pesos)
Comoros Round up the fare
Congo, Dem. Rep. Round up the fare
Congo, Repub. of the Generally no tip, however some may ask for one. Rounding up the fare is never a bad idea
Cook Islands Generally no tip, rounding up the fare is never a bad idea
Costa Rica round up the fare for short distances, for longer distances 3-5$
Cote d’Ivoire Taxi  rides are often bargained so there is no need to tip, otherwise drivers expect 10 percent with the Taximeter.
Croatia It is common, but not obligatory, to round up to the nearest kuna on a fare.
Cuba It depends on the length of the ride. If the price is fixed, a tip isn’t necessary as you can assume you’re being overpriced. Otherwise rounding up the fare is appreciated. 
Cyprus Round up the fare or 5-10 %
Czech RepublicRound up the fare, unless you have a fixed price.
Denmark Generally not expected, but can let them keep the change or round up the fare.
Djibouti Round up the fare, unless the price is bargained.
Dominica Tip 10% to 15% of the fare, though tips are not always expected.
Dominican Republic If the price is fixed, tipping is not necessary, unless the price is low. Otherwise rounding up the fare is good, up to 5 $, depending on lenght of the ride
East Timor Round up the fare
Ecuador Round up the fare
Egypt not necessary especially if you agreed the fare in advance, not more than 10% of the metered fare
El Salvador Taxi drivers don’t expect a tip, especially if the price is fixed, other wise round up the fare
Equatorial Guinea 10%
Eritrea Round up the fare or 5-10 %
Estonia round up the bill, unless theres a fixed fee
Ethiopia You aren’t expected to tip Taxi because prices are being negotiated
Faroe Islands Generally not expected, but can let them keep the change or round up the fare.
Fiji Round up the fare
Finland Finnish taxi drivers don’t expect their passengers to give a tip. In case you want, round up the bill to the nearest figure. 
France round up or offer 5 percent
French Guiana Not expected, rounding up the fair is appreciated.
French Polynesia Round up the fare
Gabon Round up the fare
Gambia, The Not common, unless they do an extra effort, like carrying luggage. Then 50 cent are ok. 
Gaza Strip Round up the fare
Georgia 10%
Germany 10%
Ghana 5-10 %
Gibraltar Up to 3 £ depending on length of ride and amount of bags (for longer rides 5 £ can be suitable).
Greece Round up the fare to the nearest Euro, for longer distances 5-10 % is a good marker.
Greenland Generally not expected, but can let them keep the change or round up the fare.
Grenada 10-15 %
Guadeloupe Up to 10 % depending on kindness and helpfulness with bags.
Guam 10-15 %
Guatemala Round up the fare
Guernsey Round up the fare
Guinea Round up the fare
Guinea-Bissau Round up the fare
Guyana 10-15 %
Haiti Round up the fare
Honduras Not customary.
Hong Kong Round up the change, although some taxi drivers won’t take tips at all
Hungary around 10 %. Important: Only use official taxi companies and check the route. Sometimes they use high fares.
Iceland Not expected
India Round up the fare.
Indonesia Round up the fare.
Iran Generally not necessary. If you have the taxi for a longer ride or the whole day, you can add 15-20 %.
Iraq Not common, rounding up the fare is ok
Ireland Not mandatory, rounding up the fare is appreciated (next 5 or 10 €)
Isle of Man  Round up the fare, if service was excellent (e.g. helping with baggages) you can round up to 10-15 % of the price 
Israel Rounding up the fare is common, but not mandatory.
Italy Round up the fare
Jamaica Although you set the price with the taxi driver beforehand, a 10 percent to 15 percent tip for taxi drivers is customary.
Japan No tipping
Jersey Not expected, if service was good, round up the fare
Jordan Round up the fare
Kazakhstan Not common, if theres a meter, round up the fare. But generally there are fixed charges.
Kenya Round up the bill to the nexst 100 or 200 Ksh, depending on length of the ride
Kiribati Round up the fare
Korea, North Included in the tour
Korea, South Not recommended, you can let the driver keep the change.
KosovoNot expected, if yes round up to the nearest Euro
Kuwait Round up the fare
Kyrgyzstan Not expected since prices are negotiated beforehand
Laos Round up the fare; ofen price is negotiated before
Latvia Round up the fare (1-2 €)
Lebanon Round up the fare up to 5000 LL
Lesotho 10-15%
Liberia 10%
Libya Tipping is not common in Libya., except maybe for tour guides (round up the fare)
Liechtenstein Round up the fare (2-3 CHF)
Lithuania Not common, if you pay cash you can round up the bill
Luxembourg 10%
Macau Round up the fare
North Macedonia Set your rate before you get into the car, then no tip is required, unless you had e great service (then you can add a little extra)
Madagascar round up the fare
Malawi round up the bill, unless theres a fixed fee
Malaysia not required
Maldives not required (there arent many taxi rides, if yes, round up the bill)
Mali round up the bill
Malta 5-10%
Marshall Islands Not expected, but rounding up the bill is appreciated.
Martinique Round up the fare
Mauritania Round up the fare.
Mauritius Prices are normally negotiated, if service was good you can add 100-200 MUR
Mayotte Round up the fare.
Mexico Not expected, if service was good, round up the fare to about 10-15 pesos
Micronesia, Fed. St. Round up the fare.
Moldova Round up the fare.
Monaco round up or offer 5 percent
Mongolia Round up the bill. If the ride was long 10-20 % could be suitable (drivers on tours).
Montserrat 10%
MontenegroRound up to the nearest Euro or 5-10 %
Morocco Generally not expected due to fixed prices, if service was very good you can add e couple of DH (if a taxometer is used you can add 10-20 DH)
Mozambique If prices are fixed there is no need, if not, round up the fare
Namibia Round up the fare; above 30 min tip 10 %
Nauru 10 % or even small change can be sufficient
Nepal Generally not required, if yes round up the fare (if they use the meter)
Netherlands Round up the fare
New Caledonia Round up the fare
New Zealand Round up to nearest $1, $5 or $10 (depending on length of the ride)
Nicaragua 5-10 %, if the price isn’t fixed
Niger 10 % or even small change can be sufficient
Nigeria No tip required due to probably higher prices for tourists. If the price seems reasonable you can round up the fare.
N. Mariana Islands Round up the fare
Norway Round up the fare
Oman Not necessary especially if you agreed the fare in advance.
Pakistan Not expected 0-30 rupees is appreciated (up to 0.2 $)
Palau Round up the fare
Panama round up the bill, unless theres a fixed fee
Papua New Guinea round up the bill, unless theres a fixed fee
Paraguay Round up to the nearest 1000-2000 guarani
Peru Taxis do not expect tips. Fares are negotiated prior to initiating the trip.
Philippines round up to the nearest 20 or 50 peso
Poland Round up the bill (unless price is fixed).
Portugal 10 % of the fare.
Puerto Rico 10-15%
Qatar 5-10 QR, but not always expected (especially not, when fixed price)
Reunion Round up the fare, unless the price is bargained.
Romania Round up the fare, unless you have a fixed price.
Russia 5-10 %
Rwanda Round up the bill (unless price is fixed).
Saint Helena Round up the bill (unless price is fixed).
Saint Kitts & Nevis 10%
Saint Lucia 10%
St Pierre & Miquelon Round up the fare
Saint Vincent and the Grenadines Round up the fare
Samoa Round up the fare
San Marino Round up the fare
Sao Tome & Principe 5-10 %
Saudi Arabia 10%
Senegal Not expected due to fixed prices. If a taxometer is used, round up the bill
Serbia Round up the fare
Seychelles Round up the fare
Sierra Leone Round up the fare
Singapore Not expected
Slovakia Round up the fare
Slovenia Not expected, rounding up the fair is appreciated.
Solomon Islands Round up the fare
Somalia 10-15 % (except price is fixed)
South Africa 10 % of the fare.
Spain Round up the fare
Sri Lanka Add 50-100 Rs for short rides, even if prices are fixed (which is important to do)
Sudan Round up the fare
Suriname Round up the fare if the price isn’t fixed.
Swaziland 10 % unless price is fixed.
Sweden Not required, you can add a few SEK and round up the fare if service was good.
Switzerland Round up the fare (2-3 CHF)
Syria 10-20 %
Taiwan no tipping
Tajikistan not expected
Tanzania Round up the bill, if theres a fixed fee you can add 1-3 $ depending on length of the ride.
Thailand It is common and recommended to agree on a price in advance. Then there is no need to tip. Otherwise, round up the bill.
Togo Round up the fare up to 10 %, unless price is fixed.
Tonga round up the bill if there is a taxometer, if price is fix, don’t tip.
Trinidad & Tobago 10-15 %
Tunisia 10%
Turkey Round up the fare to the nearest lira, if they help with suitcases, you can tip 1-2 lira more
Turkmenistan 5-10 %
Turks & Caicos Is 10%
Tuvalu round up the bill if there is a taxometer, if price is fix, don’t tip.
Uganda Round up the fare
Ukraine Not expected, rounding up the fair is appreciated.
United Arab Emirates Round up the fare to the nearest AED5-10.
United Kingdom Round up the fare, if service was excellent (e.g. helping with baggages) you can round up to 10-15 % of the price
United States 10 % is a good marker, at least 2$
Uruguay Tipping is not common, unless you ask your driver to help you e.g with your luggage, then you can tip up to 10 %
Uzbekistan You should fix the price beforehand, thereofre no tipping is required. You can round up to the nearest 0.50 $ otherwise or if service was good.
Vanuatu Tipping or bargaining goes against local tradition with a smile or a simple ‘thank you’ considered tip enough.
Venezuela Not expected but rounding up the fare is appreciated.
Vietnam Not required (try to negotiate the price beforehand)
US Virgin Islands 10 % is a good marker, at least 2$
Wallis and Futuna Round up the fare
West Bank Round up the fare
Western Sahara Generally not expected due to fixed prices, if service was very good you can add e couple of DH (if a taxometer is used you can add 10-20 DH)
Yemen Round up the fare unless price is fixed.
Zambia Round up the fare unless price is fixed.
Zimbabwe Round up the fare unless price is fixed.