In my store, it's the cashier's responsibility to know when his/her shift is over. We shut our lights a couple minutes before the end of our shift, and we have to wipe down our belt, counter, card reader, and register. We also have to make sure all our hangers and re-shop are put back where they belong (hangers in the hanger bin and re-shop in the cart at the front of our check lanes). If the GSA/GSTL is around, I'll just say, "hey, I'm done for the day." If they're not around, I just head to the time clock.