Perhaps Canadian readers will be interested in my recent experience.

I ordered some stuff from Woodsmith costing $42.90US and they were about to
charge me $21.49US for handling and shipping via UPS. I felt this was
excessive (50% of the value of the order) so I asked them to ship it USPS
instead. They agreed and said the charge would be $16.25US. I found this
still to be expensive but I agreed to the price.

I received the package today with a charge of $12.94CAN. This is $3.70
Federal Sales Tax plus $4.24 Provincial Sales Tax plus --- wait for it ---
$5.00 service charge!!

So now I have paid $16.25US plus $12.94CAN via the postal service versus
$21.49US for UPS. I don't know if there would have been additional charges
by UPS (taxes etc). Perhaps someone can enlighten me on that point.

Even without tax considerations, it cost me $16.25US plus $5.00CAN instead
of $21.49US. Not much of a saving considering the current exchange rates
and a big loss if UPS does not collect tax.

Best Regards,
Jack Fearnley