Splitting the Tab

I'll admit that it drives me nuts when I'm out to dinner with a group of friends and as soon as the check comes, one person has to whip out her calculator to make sure she's not overcharged for the extra chips that the rest of us snacked on. I would never expect someone to pay an amount equal to everyone else if she only ordered a drink or a cup of soup, but if you ordered a salad that was two dollars less than the entrees everyone else enjoyed, I don't understand why the check can't just be split equally.

Is it so bad to over pay by a few dollars with friends? I figure that most of the time when you go out to dinner, you're paying to have some good laughs with good friends, not just a good meal. Maybe this is just one of my pet peeves, but do you ever encounter this?