EBay doesn't actually collect any money. That is done by Paypal* who then give eBay their fees based on the original currency of the listing. And collect 2.9% of the payment as their fee in the original currency. And the seller gets the rest of the money in the original currency of listing.
So if you buy an item that is $10USD, you might be charged $13.39CDNtoday and $13,25 tomorrow, but eBay would get 10% of the US dollar price ($1.00 ) and no more.
What you see on xe.com and other online exchange tracking sites is the 'mid-market' rate.
That's the rate international banks use on their multi-million dollar transactions.
This rate changes constantly during the day (and night).
Your bank has a rate that is a 'retail ' rate. It is different for buying and selling and includes bank charges and a profit margin.
Unless the loonies is doing something shocking, this rate changes only once a day.
But ask at your credit union and at a foreign exchange shop and at a different bank for their rates on the same day and you are likely to get four different numbers.
Actually eight -- again buying and selling.
Every financial institution takes fees on foreign exchange.
Every financial institution makes or wants to make a profit on exchange.
Just to be clear, the difference between the (eg) US and Canadian dollar rate is more a convenience than a rate. Again it changes with the currency market.
Which is vastly oversimplified.
*Paypal was a part of eBay until about a year ago, but they are now separate companies.
