Back in 1970 I worked for a couple of months in a convenience store.
They had a policy that you could have no more than $50 in the register at any given time. If it went over that you had to put it into the floor safe by way of a slot. We also had a key to it, but we weren't supposed to use that until we got the money out to make the night bank deposit. If someone robbed the store and told us to open up the safe we were supposed to tell them we didn't have the key.
Yeah right. Someone sticks a gun in your face and you're supposed to tell the robber you don't have the safe key. Put you life on the line for a days receipts at the goddamned minute market.
$50 in 1970 is roughly $300 in today's money.
http://www.bls.gov/data/inflation_calculator.htm
And I can tell you, there was no fucking way you could keep from going over that when it was busy.
I mean think about that. You got a store full of customers, and people waiting in line. And you're supposed to stop everything, take a big of cash out of the register, and put it in the safe.
It was just a way for the management to transfer the robbery risk to the employees.