How to Add a New Currency [Tutorial]
I've written up a tutorial on how to add a new currency to your Vantage site.
http://docs.appthemes.com/tutorials/...-new-currency/
Remember, while you have a custom currency selected, payment gateways will probably error when you try to use them. It is recommended that you turn off all payment gateways like PayPal, Google Wallet, Stripe, etc. Bank Transfer and similar gateways should be the only type of gateway turned on when using a non-standard currency.