The way things worked at the place I was a server at is the waiters would keep all the cash from all the bills then settle up with a manager at the end of the night. They look at the computer to see what your sales were, you give them that amount from the cash you were holding and anything left was your tip.

Of course, if you could make that number, the sales of the night, go down without changing how much cash you were holding, then the amount left in your pocket was bigger.

So we'd take orders, ring it in like normal, give people their bills and collect the money like normal... Then after they'd left, we'd add discounts to the bill. We had a few small ones that we could give without manager's discretion, $5 senior discount, 10% off as a complimentary deduction(meant for like if you get the order wrong or something, but not enough to comp the whole meal). We already had the cash for the full bill, so the discount was money straight in our pocket.

We'd only do it occasionally, like if we got stiffed or something. If anyone really, really wanted to scrutinize our checks they'd probably see a higher than normal number of "seniors" ate at our restaurant, but no real definitive proof. (and no one cared enough to look that much into it anyway).

I don't exactly feel good about it, I mean it is theft, but they weren't exactly entirely thorough about respecting employee's rights, so I don't feel real bad about it either.