I have shipped (cigar's) Canada a few times (~6 or 7). I just had my first problem last week using USPS Express Mail. I think it's hit or miss as I have always been honest on the customs form. They tried to charge the person I sent the package to $115 in taxes for $90 worth of cigars. F'n ridiculous.

I'm going to try again being a little vaguer on the custom's form to see how that works out.