I was looking for the thread to post my confirmation of it working today with Bioshock Infinite. I was tempted to do the Tomb Raider, but I'm pretty sure I would have been turned away like some others on the forum for that $1, so the $20 didnt look too weird. When I did get ready to do it, apparently word got out about people doing this to take advantage of the deal the clerk wasnt sure if she could process it, but the manager basically said if the system applies it, then its valid.
PM'd Amazon Bioshock Infinite for 39.99, Bought a GTA V preorder card, total came out to $22 after tax. So its definitely still working . If anything just say you called ahead of time and said you were told on the phone that it was ok as long as the system accepts it.