The Rock Supply Co. uses the perpetual inventory procedure and the LIFO method of inventory costing. Following are inventory data for 2017.

Purchases Sales

January 10 600 units at $8.00 March 17 400 units

March 15 800 units at $7.60 October 5 1,300 units

May 18 500 units at $8.20

December 30 600 units at $8.00

If there was no beginning inventory, the cost of the ending inventory is:

$6,400

$7,080

$6,880

$8,030