When I worked in a drug store many many years ago, we closed every night around 9pm.
The thing that sucked about this was when people would come into the store at 8:55pm and start shopping around.
One of the rules in our store was that we couldn't tell them we were closing, we just had to ask them if they needed any help and wait for them to leave the store.
That never worked with me. I had no patience for people 'browsing' at 9 o'clock, especially when the same people did this all the time and knew perfectly well when we closed.
When someone came into the store right before closing, I'd quickly have an inward temper tantrum, and then I would wait until the clock hit exactly 9pm. Then I would go into the back room and start flipping off certain lights in the store to give them a hint that we were closing.
If that didn't work, I'd walk towards the front of the store and yell out to my coworker that it was 9 o'clock and that she could lock the doors now.
If the customer still hadn't gotten the hint, I'd walk up to them and ask them if they needed any help. Most of the time I heard, "Nope. Just looking." which pissed me off even more.
Since I didn't really care about the rules, I'd then tell them that we were closed.
"Oh, you are?" was what I usually heard, and that's when they'd glance around at the store, finally noticing that we were standing in the dark from all the lights being shut off.
Fortunately for me, (yeah right), the place I'm at now is open 24 hours. So people can come in and 'browse' whenever they want.