They never charge your card the first time. It's a temporary hold just to confirm that there's funding in the account you're using. If you used PayPal, it even says the amount could change when they finally do process and charge your card. The exchange rate can also change, plus your credit card/bank fees can affect the price, plus whatever fees HTS incurs. I've had to pay fees buying internationally, I'd imagine it's even more expensive for a business.