$1.$ Record the inventory, purchases, and cost of goods sold data in a perpetual inventory record similar to the one illustrated in Exhibit $4,$ using the last$-$in$,$ first$-$out method. Under LIFO, if units are in inventory at two different costs, enter the units with the HIGHER unit cost first in the Cost of Goods Sold Unit Cost column and LOWER unit cost first in the Inventory Unit Cost column. Round unit cost to two decimal places, if necessary.