It is up to each retail store to set its own policy with regard to refunds and exchanges. There is no legal requirement for a store to give you back your money after a purchase. Even if the merchandise is defective, the merchant may choose to give you another item or a credit.
(Many states or localities have regulations regarding the posting of whatever the store policy is: for instance, that the policy must be on the merchandise tag, on the sales receipt, or on a sign by the cash register.)
Refunds, Exchanges and Returns - A Customer Service