The term "sales check" can have multiple synonyms depending on the context in which it is used. In retail, a sales check is often referred to as a receipt or sales slip. In accounting, sales checks are typically called invoices. Other terms that could be used as synonyms for sales check are purchase order, transaction record, or sales receipt. Depending on the industry and the specific type of purchase being made, alternative terms may include checkout slip, order confirmation, or bill of sale. It's important to choose the appropriate synonym based on the context and purpose of the document.