You know in Europe service, around 10-15%, is automatically added to all the restaurant bills.
If you want to leave more, you leave maybe 5%, il resto, plus or minus, when you leave the restaurant.
I can live with that.
Maybe I'm being too picky, but if folks are going to charge a service fee, they should call it that--a "service fee"--rather than a "tip"!
For the record, I usually tip 15 - 30% depending on the server(s). :-)