the 5 or 10 creditts would not be taxable. they usually give those because it messed up. an order got lost etc.
the $200 for opening a credit card may be a different story. is this any different than the $200 (or more) that banks often give when you open an account? It's usually reported on a 1099-INT. I don't think so, but then if it was taxable Amazon should have informed you and also sent you a 1099-INT. it did get your SSN.
