I consider myself a good tipper, always rounding up to at least 20%, even more when the service deserves it. Thankfully, Kris is the same way, sometimes even more so. But that's not always the case. The Wall Street Journal discusses the different view points on the hotly contested value of tipping. The following quote sums up my reason for rounding up:
"In the end, the difference between a 15% tip and a 20% tip really only amounts to a few extra dollars out of my pocket, but it can make a lot of difference to the person receiving the tip. If you're dining at the restaurant, chances are you make more money than the people waiting on you. As a percentage of income, those few extra dollars make a far bigger difference to a waiter or waitress than to you -- especially if other patrons adopt the same strategy."
So there you have it. If you make sure my glass it topped off, clear my place when I'm finished, and just be friendly, I will make sure that you know you earned it. Bonus points for establishing a connection through a conversation or offering a particular menu item you enjoy. However, being directly rude or cruel will make me keep the extra bucks in my pocket.