Q 5.1: Which of the following statements is NOT true regarding a perpetual inventory system? A All of these statements about perpetual inventory systems are true. B The inventory account is updated each time a purchase or sale is made. Perpetual inventory systems have traditionally been used by businesses that sell a relatively low volume of higher priced items such as automotive dealerships. Cost of Goods Sold is determined at the end of the accounting period in a perpetual inventory system and is based on a physical count of goods on hand.