Use the first$-$in$,$ first$-$out method to find the cost of ending inventory using the following table and the fact that the ending inventory is $500$ units:

Date of purchase

Number of Units purchased

Cost per unit

Begin Inv.

$221$

$$16$

April $15$

$328$

$$15$

May $12$

$167$

$$12$

June $5$

$201$

$$9$