Davem17, A lot of places don’t allow this to happen anymore, which is a shame. I have had some people behind the bar say thank you, they will save it for after their shift, cause they are not allowed to drink while working. Personally, I always tip, never a certain percentage, but I always leave something, the better the service, the better the tip.
I only know one person who doesn’t tip, and my friends and I are always embarrassed by her. 12 of us went out for a meal just before christmas and she got in a right mood because we agreed to put a fiver in the pot each and leave them the change from the bill.