Originally Posted by
QueenOfCoach
Good question. By experience, living and working in the US, I know where tipping is customary and where it is not. If you are not a US resident and truly do not know where tipping is customary, you are well advised to ask someone when you first come to the US for a visit.
But even within the US, where you tip, and how much you tip varies hugely - I would doubt a US citizen would be 100% 'right' (and by right I mean doing what the vast majority do, i.e. what is customary for that place) all the time.
Now that someone has pointed out that the IRS assume 8%, it does make me wonder why people tip double that, as that is clearly what the IRS assumes to be reasonable.