When a package is ordered by a citizen living in Manitoba, for example, which has a PST, if the package crosses the border in Manitoba, the GST and the PST will be collected. If the same package is coming to Canada, going to Manitoba but crossing into Ontario, the GST will be collected, not the PST, because there's an agreement between the province and the federal government that only the GST will be collected.
Those agreements, in most cases, are very old, and were put in place before the growth of e-commerce, when people were not ordering online.
If the package is coming through a province with HST, so Ontario and going to an Ontario customer, the GST is collected, and there's a formula to calculate the HST, the provincial part, that will go to the province. It's called the revenue allocation framework. It's very technical. I will not go there, but this is basically the picture of the situation.