Autodetecting Currency Module

Ive searched this forum and the website but cannot find what im looking for, a client of mine is wanting an ecommerce system but with an autodetecting currency plugin so that visitors to the site get the correct currency for their country, i want to use opencart as its so great but wanted to know if a plugin exists or whether one is in development, any replies gratefully received!

I have this here
http://theqdomain.com/ocstore/country-currency

Thanks, looks just like what ive been looking for!