Since it seems tipping is a hot topic right now, let me add this. I have a girlfriend that I go out with, that I have had to educate about tipping. We used to work together and run up to a salad bar for lunch. It was always dutch treat, and you pay before you get your salad. The first time, at the end of the meal, I pulled out a buck for the server (meal cost $5.49) and she asked why did I do that. I was dumbfounded. I explained that the server kept our drinks full, cleared our plates, and went in search of melba toast when there wasn't any in the basket. So she says "well that can cover both of us." I told her it would be fair if she at least pitched in a bit. Now this is a woman who made good money, and her DH made tons, so it's not that she didn't have it to spare. I explained the way it works in the restaurant business and I thought it took.
Then we went out with another friend to a bar to see a band. She started a tab, and I figured we would split it at the end. When we did get the tab, she volunteered to treat us, but left a measly tip. I slipped away to the restroom, and then took the bartender to the side and slipped him my share of the bill. He was very appreciative. Now that I know she is a cheap tipper, I always make a point to add the tip amount when we figure out how to divvy it up, or if she treats, then I leave the tip myself. I do it in honor of my daughters who have both been servers and bartenders!