Not sure how or if it is enforceable (or applicable) for goods ordered from SXM, but not shipped to SXM. Amazon certainly charges the appropriate federal and provincial sales tax here in Canada, based on the province of residence, for any goods purchased online. It's also our experience with any other online vendor.

It makes no difference as to whether the goods are sourced here in Canada, or shipped in from somewhere else, such as the USA. I've never tried ordering online for shipment to some other country, so not sure how that would work. Certainly anything we have ordered online from retailers for use here at home, the tax is always applied. I believe that is the case in many other countries, too.