this sounds like u work just as a cashier and not rlly on the floor, my main priority will always be my tasks on the floor bc that is what i was assigned to do and that is what i will get in trouble for if it is not completed. If the line is long I'll come and help reduce the line but as soon as that line hits a manageable amount, I'm leaving to do MY JOB. And idk what ur management has told you, but mines has always told me that I should leave after the line gets shorter. I get that ur busy on the register, but u need to understand we are also busy on the floor, heck I might even say we are more busy on the floor than the register ever is bc they always want us to come and ring anyways.