They keep a minimum amount of cash, CCTV and have trained the employee
to just give that small amount of money. Any robber that goes to a place like that knows that there is only so much money available, no more.
Any potential robber understands that at the first of the month after everyone's picked up their welfare checks and make their monthly run on cigarettes that it's not uncommon for those registers to have $10-$15K in cash in them.
That's why I laugh at those signs that say "No more than $100 on hand" or "No more than $250 on hand"
I've counted more cash out of a tobacco register than I made in two months before because it was the first of the month.