Stillwater, which uses a perpetual system, sold 995 units for $23 each during the year. Sales occurred on the following dates: Calculate ending inventory and cost of goods sold for each of the following three methods: In your calculations, round average unit cost to three decimal places. Round all other calculations and your final answer to the nearest dollar. Which method(s) give(s) a different answer depending on whether a company uses a periodic or a perpetual inventory system