The wrong way to steal money
When I worked at a bookstore in college, I was indirectly responsible for another employee embezzling money from the company. I can't say I am particularly proud of this fact, but I can say the other employee was an idiot and did a very poor job of following my near-perfect salary enhancing scheme.
Having watched the various buying habits of people in the area, as well as the inventory techniques of the store, I discussed a return-refund technique to the assistant manager of the store. The technique worked something like this: a customer would purchase a fairly expensive book, or a small number of relatively expensive books, say hardback books, in cash. The transaction could be anywhere from $20 to $100 in books, the key was the customer paid in cash.
The very next transaction would be a refund for one of the books sold on the previous purchase or a cancel of the entire purchase if the purchase was for one expensive book. The situation would actually happen regularly enough that it wasn't unusual for a return immediately following a transaction: often the customer wouldn't have enough money, so it was easier to ring the transaction as cash and refund one of the books on the next transaction or cancel the purchase completely on the next transaction.
The cancel or refund would happen on the next transaction, but only after the customer had already left the store. The refund or cancelled transaction amount could then be pocketed. This technique would work well on a slow day, when the customer would have left the store and not see the transaction, or possibly on a busy day if the clerk was quick enough to cancel the transaction between customers in line.
The amount pocketed would never be much: $20 or $40 at a time, and the situation had be correct: a cash transaction followed by an immediate cancel of the transaction. The cash could be removed from the register at the end of the evening when the drawer was counted out.
Since the store didn't have any surveillance cameras, there wouldn't be any direct evidence of theft. The trick would be to avoid any patterns in the transaction cancellations, and not doing it more than once or twice a month at most for small amounts, lunch money for a couple days at most.
So, yeah, the technique was fairly foolproof. I just wasn't counting on a real fool.
I arrived into work one day, to find out the assistant manager had been fired and the whole store was being both inventoried and audited. A few weeks later, my manager would be fired and charged with embezzlement for having "borrowed" hundreds of books without returning them. The store had a borrow policy that employees could borrow any book as long as it was returned in sellable condition. Books were signed out on the sign-out sheet; the manager would sign them back in if they were over a week overdue. He rarely returned his books.
The assistant manager, however, was the trigger for this mass audit of the store. It turns out, he attempted my return-refund technique, but not in its proposed form.
Instead of cancelling cash transactions, he would cancel charged transactions, and pocket the money he refunded. The problem with his version of the technique was not only was the customer not charged for the transaction (since his card was refunded), but the drawer was short by the amount of money the assistant manager stole. The trail of theft was ridiculously easy to follow (nice paper trail), made easier by the frequency of thefts.
When I heard of the disaster, I was immediately mortified. He was doing what I had suggested, admittedly suggested in passing and not seriously, but my idea none-the-less.
Because of this experience, I'm more observant to when cashiers hand me merchandise and put aside the cash I pay them. Like today, at the fast food place in the Atlanta airport. After struggling to understand the woman wasn't asking me if I wanted a drink with my pizza, but rather was saying my total was $5.22, I handed her $11 as a single and a ten. I expected a five dollar bill plus change back. Instead, the cashier eyed my remaining four singles. She asked for them, handing me back my $10 bill. I fished for a quarter in my backpack as she handed me my pizza.
Now, it's entirely possible she needed singles and twenty two cents was a small cost to pay for the five singles I had. But I doubt it. I'd be very surprised if under the register is the correct place to put the five dollars destined for the register.