My experience ordering from outside Canada - say past 5 years - about a dozen times - perhaps one out of three parcels to me get dinged by Canada Customs for GST / PST - I have never had to pay "duty" on slings, scope rings, gun parts, screws, etc. So maybe $3 GST / PST on the value - then parcel continues to local Post Office - I have to pay an additional $9.95 (?) as a "collection fee" - (so now total to pay is $3 GST/PST plus $9.95 = $12.95) I thought that the $10 goes to Post Office and the GST goes to Fed government, and PST goes to province. And about 2 out of three parcels just arrive for me - I can not figure out what triggers that tax assessment - I have had to pay for smaller value than larger value parcels - is no sense to it that I can figure out - as if random.
Totally separate from courier "brokerage fees" - perhaps 20 years ago, I ordered item from USA - I paid the Seller for the item and shipping - sent by courier - the Seller paid the courier for shipping - item arrived - then I received a bill for the courier "brokerage fee" - was last time that I used a courier to bring something into Canada to me.