I think both UPS and FedEX work the same way - they buyer has to pay extra "brokerage fees" when they receive the item. These fees can be significant. I forget the amount, but it could be something like $30 + taxes owed. That can be significant on small items.
The other alternative is to pay for a higher tier of shipping, something like "International Priority". Not sure the name, but both UPS and FedEX have this upgrade, each with their own name for it. In this case "brokerage fees" are included in the ship amount, but the ship amount can be quite a lot higher. I believe taxes are still collected, but that extra $30 or so is not added. I don't know what the exact details are, but I'll be cynical and say that it probably amounts to a small cost to upgrade the shipping method, but the same extra $30 added each way, so still a rip off!
The best way to avoid this IMO is to ship small items by USPS. USPS *without tracking* will be charged by the Canadian post office at $5CAD + taxes charged. UPS *with tracking* will cost more up front, but will still be the same charge, $5 + taxes owed.
So, small items, USPS without tracking (optionally marked as lower value or "gift" to avoid taxes). No insurange or tracking, so someone, usually buyer, must assume responsibility for loss. Medium value items, use USPS with tracking, valueable items UPS or FedEX Prioirty (verify brokerage fees before paying higher shipping charges). That is what I would do.
Richard