When you sell something through your website a third party, the E-Commerce Integration provider, takes a cut. The cut is based on the account you set up with this provider and the exact amount charged depends on the default currency of the account.
There is nothing from stopping you setting up multiple accounts.
At the point of payment an E-Commerce developer could check the origin of the user and flip the gateway over to the account that will incur minimum charges.
For instance, the well known E-Commerce provider Stripe has these different charges for different payments:
Australia: 1.75% + 30¢
USA: 2.9% + 30¢
This model could be extended to more than two countries if need be and can result in substantial cost savings for websites with a large number of international transactions.