Well, with receipts you have a 90 day window ... so if he's returning them within that window, then he's really not doing anything sketchy because that's really Home Depot's policy and intent. They tend to be pretty lax with returns. He may have brought the receipts, been outside of that window, and the cashier simply told him to take away the receipts because it was too long ago, scanned his driver's license, and gave him store credit anyway.

Lowes, Ikea, Bed Bath and Beyond, they all operate the same way. They'd much rather you buy lots of stuff and return some of it, then buy a few things.