Check with your bank most of them have a US credit card and you won't be charged the 2.5 % for using it in the US. I just get one from TD Canadatrust and I have heard that BMO has one with no annual fee.
If you travel to the US alot you can always get a Target visa but the down fall is you have to either mail your payment in which takes weeks for them to get or go to a target store to make a payment.