Technically, every package should result in your having to pay, unless the contents of that package are not subject to any of the following:
1) GST/HST,
2) provincial sales tax,
3) customs duty,
4) excise tax,
5) excise duty,
6) provincial liquor tax,
7) or .....
Practically speaking, and as a matter of policy, the Border Services and customs and other taxation enforcement staff are directed to exercise a tremendous amount of discretion, and as a result a large number of personal importations proceed without any such taxes or levies being charged. As I understand it, this policy is the way that it is in order to encourage cross-border traffic.
The policies do not extend to commercial importations. For that reason, if the Border Services and customs and other taxation enforcement staff believe that your package has a commercial purpose (it's either for re-sale or to be used in a commercial operation - this includes commercial photography) than they are required to charge those taxes and levies.
Matt