SolarWave Inc. uses a periodic inventory system and has the following data for the month of September:

Date	Description	Units	Unit Cost	Total Cost
Sep. 1	Beginning Inventory	100	$50	$5,000
Sep. 10	Purchase	300	$52	$15,600
Sep. 15	Purchase	200	$54	$10,800
Sep. 20	Sale	400	-	-
Sep. 25	Purchase	400	$55	$22,000
Sep. 30	Sale	500	-	-

Specific identification details: the September 20 sale consisted of 100 units from beginning inventory and 300 units from the September 10 purchase; the September 30 sale consisted of 200 units from the September 15 purchase and 300 units from the September 25 purchase.

Required:

1. Calculate the ending inventory using FIFO, LIFO, and specific identification methods.
2. Determine the COGS using the weighted average cost method.
3. Assess the impact of each inventory method on the gross profit.
4. Discuss the tax implications of using LIFO vs. FIFO for SolarWave Inc.