At this time, all purchases made through the Desktop or Mobile site will be processed in USD($). If your local currency is different, your bank will process the purchase and convert it based on the current exchange rate. We do not have a way to show you pricing in your local currency before you complete your purchase, but we're hoping to offer this service in the upcoming months, starting with GBP.
If you're purchasing Coins through the Paperless Post iOS app, you may see your pricing in your local currency. Checkout through the app is completed via the iTunes store, and is subject to Apple's terms of service.