Every wireless plan is different, and even a plan from Rogers that you buy today could be different than the one someone may have obtained a year ago. That's because the companies are constantly changing what is and what is not covered.
When I cross the border with my phone, it immediately switches from my present service to AT&T and shows "Roaming". If your contract does not have any special deal about roaming charges, odds are you will get billed for any calls you make when roaming.
But you really should call up Rogers Customer Service to get more info. I think this is as simple as dialing *611 on a Rogers cellphone. If you don't have a cellphone with Rogers (just the tablet), then I think the number is 1-888-ROGERS1.