When you submit your feed with your product data to Google's Merchant Center, you need to use a language and also a currency that’s supported for your target country. Ideally the currency of your website and the currency of your target country match. In case they don't, you can make use of Google's currency conversion tool. This tool can be used to help expand the reach of your products to more countries by automatically converting the original currency to the required currency in the target country. The converted price estimate shown in your ads is based on exchange rates from Google Finance. Please keep in mind that you also have to meet the target country’s language requirements. Here you can check the currencies used for each country in Google Shopping.