Your actual costs are more than the postage. They include packaging costs, insurance, and fees. Some of these are required by eBay to be part of the asking price.
Don't forget that Canada Post will charge you sales tax and a fuel premium.
Packaging is called a Handling Fee and can be added to your Calculated Shipping if you like. It is not broken out on the invoice, so if your customer sees $3.85 for shipping and handling, she can believe that the postage is $3.85 even if tax, fuel, and bubble wrap costs make up $ 1.36 of that.
If you want $10 for an item and fees will be $2 and insurance another $0.10, then your asking price should be $12.10.
