Around here, Lowes and Home Depot give you the first two cuts for free, then 50¢ per after that.
Do call them first and check that the panel saw is working. At the HD near my home, it’s was as often broken as it is working until they replaced it recently.
Also, be sure to know the size pieces you need. “About” will probably win you a blank stare. And, be ready to pick a piece of plywood (watch out for bashed corners, splits, and other assorted uglies) and bring it to the saw. They’re not completely full-service. 