In this subtitle the following words have the meanings indicated. “Cash” means United States coins and currency. “Cash” does not include: a paper instrument other than a Federal Reserve note; or a gift card. “Customer” means a purchaser of a good or service from a merchant. “Merchant” means a person engaged in the trade or business of the sale of goods or services. “Price” means the amount due and payable by a customer for a good or service after a merchant: subtracts any discount or deduction; and applies any applicable tax or fee.