Most likely your seller had $5 as the domestic (US) shipping price. When you placed your bid, eBay used your location to show the Canadian shipping cost.
While shipping with Delivery Confirmation is very cheap in the USA, shipping to Canada with DC costs $21 and up. It is a good idea , before bidding, to look at the Shipping tab, to confirm that the seller does ship to Canada (many won't) and what the charge will be.
Then, you can politely request that shipping be by First Class International. While this is much cheaper, it is the seller's choice whether he agrees or not, since without DC he is opening himself to fraudulent claims. If he does not agree, don't bid.
One other thought. The seller may have given a choice of shipping services, with the more expensive one being the default. Contact him and explain that you would prefer the cheaper one.
Finally, you can within limits, cancel your own bid. This will show on your feedback page and some sellers may cancel your future bids because of your cancellations. Or you can politely ask the seller to cancel your bid, based on your surprise at the shipping cost. Again, he can decline to do this.
Many 99 cent auctions are set up by sellers who either are ignorant of good selling practices or conversely are very knowledgeable and expect that the final price will be much higher. The former usually have low feedback. A peek at the feedback of the latter will often show the actual price his goods sell for, as opposed to the low opening bid.
