It depends where you are ordering from. If you are ordering from major American department stores likes Saks or Bergdorf then no customs or tax would be charged. Even if you are ordering from Europe, it is still more economical to ship to the US than Canada, as they have lower import duties. When I order items on Farfetch, I always ship to the States because it costs less even when shipped from European boutiques. Also you'll want to remember that taxes on top of duties are always higher in Canada than in the US.