Sales, as used throughout this chapter, are gross sales, and they are thus recorded in the appropriate account classification. Discounts on sales are to be shown as separate items and thus recorded in the appropriate accounts. "Returns" refer to products which have no further use and which are returned for credit and ultimate discard. Invoices and statements shall always indicate gross sales prices and discounts. Invoices shall not be prepared or recorded as "net of discount."
7 Pa. Code § 149.22