You are registered to collect tax? The listings that I checked do have tax rates set up but they are not all correct. In non hst provinces you should only be charging gst, The information is available under the shipping tab but it is a good idea to mention it in the description are as well.
I did a test on one of your items and I would have had to pay gst in Alberta. Is it possible that you are just not noticing the tax on the invoices?
Item (1) | C $5.99 |
Shipping | C $3.50 |
Sales tax | C $0.47 |