Lots and lots of misinformation spewed out here. If you don't know or aren't sure, don't speculate.
It's really random. As far as duties
are concerned, Matt got it exactly right. Unless the shipper has explicitly declared that the goods were manufactured outside of NAFTA, you won't be billed for duties. Thousands of packages move in and out each day, CBSA does not have time to figure out the origin of each and every package. This applies for packages mailed in. Bringing it in through customs yourself (by plane, car, or boat) is a different beast. You can find out how much you should
be billed with the following document: http://www.cbsa-asfc.gc.ca/trade-com...-01-99-eng.pdf
is where you usually will be responsible for. This is the HST (13%) in Ontario, or whatever is equivalent in your province.
As for exemptions
: anything under $20 is not charged tax nor duties. Packages declared as "gifts" are exempt from taxes and duties up to $60. If you exceed your gift exemption, you pay taxes/duties on the difference.
is carrier specific. You are charged this for basically "borrowing" UPS/USPS/Canada Post/FedEx's money for crossing the border with your items when tax or duties need to be collected. Canada Post/USPS from what I know charges a flat rate of $5, while FedEx and UPS will probably rape you. You can easily Google this to find prices.
In short, if you don't care about how quickly you receive your items and go with EMS/CP/USPS and with something that takes weeks to arrive - you will likely not need to pay at the doorstep. Want speed? Pay for it.