You could include a currency in the prices displayed by price.js, like so:
var xproductid1 = "9.99 USD" //name of product 1
var xproductid2 = "4.99 USD" //name of product 2
var xproductid3 = "49.99 USD" //name of product 3
Of course, the actual price and currency of each product is set in Seller Admin, so this approach would only be useful to ease keeping the displayed price/currency on your sales page up to date. While it is not possible to set multiple prices in differing currencies for a single product, you can create duplicate products that each have a different pricing currency. Regardless of your pricing currency, buyers worldwide will be able to pay you in that currency, and their payment processor or card issuer would automatically convert that amount to their native currency.