Post is a little misleading (to mean anyways). The promotion is not cash in $40 and get a $10 gift card ($40 cash plus $10 gift card). It is get a gift card instead of cash... IE cash in your change of $40 and get a $50 gift card instead of $40. Meaning you will get no money at the machine for your deposit.
Additionally of course this offer is only valid at participating machines.