We go out to eat maybe once a week at a sit down take your order place and my wife handles paying and tipping the girl who is the 22 year old daughter of a good friend. I don't know how much but my wife is a generous sort. All other times if possible and when travelling most of the time I go to a place where I can walk up to the counter and get my stuff and refill my own drink. Saving a dollar here and there mounts up mightily over a lifetime. This year at the Hastings Nebraska Subway I was directly asked for a tip by the girl that handed me a sandwich. She didn't get one.
