Ask a guy at your local Everything Mart retailer (ie. walmart, target, etc.) and ask if they'll give you a couple of those sheets they put on the thing that you sign when using your credit card. When I worked at target, we used them a lot to prevent people from scratching the machines' screens(People actually try to use a real pen instead of the stylus!). There's a good chance the cashier won't mind, and you can just cut to fit.