Here comes some unsolicited advice on how to handle the "too much work" situation that has worked for me for my entire 35 working years. Of course, my experience has been completely in a corporate environment, not in a retail store. Also, I left Staples last year after 7 years there, and I was fortunate enough to find greener pastures.
Go to your manager with the list of things you are to do, tell them that you can't do it all, and ask them to help you prioritize the items on your list. Do not be confrontational - be factual. Before you say "they'll just fire me" - if Staples is in such a hiring dilemma as stated in other posts (and I believe it is), it would not make sense for a manager to get rid of you IF you are as good as you think you are. That would make their job even harder.
Otherwise, if you can't find a job with another company with your current skill set, you really need to re-invent yourself with skills that are in demand.