Not an easy lot...
Interestingly, most people in the back have no benefits, either. And they get scant attention from the OSHA-types for the hazards they are always (...standing up) near. A friend's son is a sous chef, wrists perpetually burned and scarred. He's been doing it for about five years. $40,000, and no bennies. In one of the big-name Boston restos, the second that he's worked in where it's the same. Because they can. Because - even good - restaurant talent in all positions is easy to come by.
Back to regular programming, I usually tip 15% and round up to the next dollar. Or 20% and rounded if the service has been stellar, including wrapping doggie bags for several people. Actually, it's win-win. I don't begrudge the extra few cents, and later I can quickly scan my cc statement and know if there's been any funny business.