Yes, I've had and kept planning to mention it here, thanks for doing so. In my case it's just a few cents but others might be hit up for more since this is a way for banks to make up for the fees they lost when government rules went into effect.
You are correct, kobo doesn't mention it anywhere when you make your purchase.
I wonder if this is credit card dependent rather than a Kobo "thing?"
I just checked my cc statement and my Kobo charges are exactly the same as the sale price.
Have you queried Kobo about whether they have any additional (hidden) charges beyond the listed sale price?
I believe it is a credit card thing, I think I remember when I was in Japan, that there was a charge on my credit card for a foreign transaction feel every time I used it. It was $.17 for the last purchase, so it's really not an issue for me. (Note: It was a separate charge, not included in the Kobo Charge, but on the same day.) I could look into my other credit cards and determine if they all charge it, but for the few books I so far have purchased from Kobo, it's not worth it to me to have to keep track of another credit to pay.
I just wasn't aware that Kobo was a Canadian company, it's not easy to figure that out on the site, in fact, I still don't think I've found anything that says the company is in Canada, just a notice from my CC company of a foreign transaction being made.
As I said, it's not a big deal to me, but I thought I would mention it so others don't get caught off guard.
Every time I purchase an ebook from Kobo, I use my checkcard, and a $5.00 fee is placed on my account. It drops off after a few days, though, and the correct amount appears.