You are entitled to whats on the meter not a red cent more .Unless you go above and beyond in your service provision .I work Dublin 8,10,12 ,Lot of cash work would expect to get 10% overall on cash work in tips .I have noticed Yanks who use to cash tip now using the card do not tip at all .Might be something to do with having to put your hand out for the change seemed demeaning but on a card its impersonal its just numbers .