If the seller discloses cost and states the added profit, the sale is cost-plus sale (مرابحة). If he simply quotes a total price without linking it to cost, it is a bargaining sale (مساومة). Both may contain profit; the difference is cost disclosure and price construction.
This rule is especially important in financing because cost-plus sale (مرابحة) is valid only when the financing remains a real sale. The sequence of ownership, possession, risk and final sale must therefore be visible in the transaction.