Always a confusing topic for us poor Americans. On the one hand we are told it is actually an insult to leave a tip and the servers are automatically compensated by a built in charge on the check.Then we are told by folks like Steve at Club O that this is not so and tipping is welcome. Willie at Club O's Perch bar has a tip bowl (which I always contribute to) I love Willie. What we have found works for us is to ignore the "noise" that this subject generates and follow our own guidelines on tipping. We have yet to be told we have insulted someone or had our tip refused.The one factor you may want to consider is that wait staff and other workers at these places are compensated much better than they are here in the US but you will be fine tipping as you would at home.
Cheers.