Tipping is a outdated practice because it was made up by restaurants who had servers work entirely for free. Civilized countries have all but moved away from it. Why should you leave a percentage? if someone orders a 100 dollar shrimp and someone else orders a 5 dollar burger but the server is equally nice the 100 dollar shrimp person should pay more? just round the number up to the nearest integer and call it a day if you really want to tip. say the bill is 17.35 you pay 18.