If you ship with Paypal, does it add fees? Also Canadian shipping is terrible.

[Mismatch]

So. 

Canadian shippings SUCKS.

I've run into a few weird things about it too.  Like, I calculated shipping with tax on the regular Canada Post website within Canada, and it came out to $13.40 with my business card.  And then I went to buy the same shipping on Paypal, and it came out $2 more expensive, even though it was supposedly taking my business card into account. 

Shipping with Paypal gives the buyer some assurance that you are using the postage money for postage and that the article was shipped.  But I'd really prefer to avoid extra shipping costs for my buyers, and at least be able to predict what those costs will be if the buyers prefer I print the labels through Paypal. 

Are Paypal shipping fees a thing, or did I miss something?