Glenn described the tax situation well, but here's a little more detail:
- GST is the federal Goods and Services Tax
- PST/RST/QST is the provincial sales tax, described by three different terms depending on which province is involved (RST is Retail Sales Tax in Manitoba, QST is Quebec Sales Tax, everyone else calls it Provincial Sales Tax)
- In some provinces, the federal and provincial sales taxes are combined, so there is just the one item of HST (Harmonized Sales Tax).
Provincial sales tax is only charged for one province, generally the one where the purchaser is receiving the product, so shipments to ETI should be charged GST at 5% plus British Columbia PST at 7%, for a total of 12%, as Michael experienced.
Unlike what I have seen in the U.S., I have never seen county or city taxes on general retail purchases in Canada.