Found this on Reddit
Looks like Microsoft are still toying around with this idea. 10% of your original purchase price would mean $6 in store credit for a $60 game. Seems pretty low but then again you'd get nothing for it anyway if there wouldn't be a way to sell it.

Looks like Microsoft are still toying around with this idea. 10% of your original purchase price would mean $6 in store credit for a $60 game. Seems pretty low but then again you'd get nothing for it anyway if there wouldn't be a way to sell it.