Snipcart won’t charge your customers in a currency based on their address. For example, if you enabled USD and AUD currencies, a customer in Australia won’t be automatically charged in AUD.
You must set the cart currency beforehand, you can refer to this part of our documentation.
Once the cart currency changes, the cart will reset automatically, so you must select the right currency before the customer starts adding items to the cart.
Lots of users will use geolocation APIs to retrieve the customer location based on their IP address and will automatically set the currency based on that, you can also combine this with a currency picker on your website.