CORRECTED - Walmart tests iPhone app checkout feature

(Corrects sixth paragraph to show $12 million figure is annual)

By Jessica Wohl

(Reuters) - Wal-Mart Stores Inc is testing a system that would allow shoppers to scan items using their iPhones and then pay at a self-checkout counter, a move that could trim checkout times and slash costs for retailers.

If the "Scan & Go" test by the world's largest retailer is successful, it has the potential to change the way people shop and pay, making the process more personal and potentially faster.

Earlier this week, Walmart invited employees with Apple Inc