Different amount payed on my bank account compared to the bill

[nikmat_71]

When I buy a product on eBay, I pay the price for the product as well as the shipping. It also happens that I have customs fees because I live in Canada. But when I look at my bank account , I notice eBay withdrawing a little more money than I agreed to pay. Why ?  Let's say I bought a product of 300$CA, I pay 22.50$CA of shipping, the total on my credit card should be 322.50$ right? It's never the case, it will be more like 348.75$. 

I really don't understand why ? 

Can someone help ?

[pjcdn2005]

If the listing was originally done on another site and is in another currency, the Canadian dollar conversion that you see is an estimate.  The currency exchange rate may change a few times a day but ebay does not update it on a live basis and the actual exchange rate is based on the live rate at the time you pay. Also, the ebay conversion does not include the percentage that either Paypal or your credit card charges as a conversion fee.