I'm Miles from the Social Care team at Shopify. Thanks so much for getting in touch about the billing of your Shopify store. At the moment, Shopify only charges in USD. There are a number of reasons for this, but the main reasons are:
We have merchants in more than 150 countries, of which the United States is our largest market. We charge in USD so that we are in the local currency of most of our merchants. Further, since we service shops worldwide, we need to charge in a currency that makes sense for everyone. USD is one of the most frictionless currencies in the world and lots of international banks don't charge the same exchange rates for it, as they would for other foreign currencies.
Even though we are a Canadian company based out of Ottawa, we do have US investors and our books are reported in USD. As a result, Shopify has always billed in USD, no matter where you are located. At the moment, there is no way to change the currency in which we charge.
I hope this helps to clarify the billing, but if you have any questions, please let me know.