Fascinating. Do people also write down the amount of tips received each hour? To make sure the boss pays for the slow hour, and it doesn't end up coming out of your own pocket anyways, from the other more busy hour? I can't believe Americans are doing that amount of maths?

When I was a pizza delivery boy, I just did the cashing-up once a day. The cash register would know how much of the money in my pocket was owed to the boss, and I got to keep the change. Only time maths was involved was when the delivery cars broke down (which they did all the time) and I had to use my own car and the boss had to compensate me for using my own car.