When rehabbing, of course, keep all your receipts for tax and file purposes. For the big stuff, take back what you don't need and get a store credit or get your cash back when you're done. But keep the little stuff. You're bound to have tons of miscellaneous leftovers like nails, screws, bags of sand, concrete mix, tubes of spackling, a pallet or two of roofing shingles, tile pieces, felt, sheetrock, mud,...
