I rented from YYC this summer and they did the rental charge + 20% for me. It did go thru and posted to my card (not just a pending charge) and then when I returned they refunded the complete rental charge + 20% and then put thru the final charge as a new completely separate transaction.

When I rent from local airports, I’ve found I’m usually charged the higher end of the deposits. Most companies it’s around $400-$500 hold recently. I’ll be interested to see if it goes up this next time.