Dynamics Innovations offers a free currency exchange rate feed updater product. It’s pretty simple to install, but being free it’s not full of a lot of bells and whistles. Essentially you install the product, run a SQL script and then setup your exchange rates in a SQL table. The SQL table holds the name of the exchange rate, from and to currencies, and whether this is an average rate.
Simply set this up to run regularly with Windows scheduler and you are good to go.
This is actually a really nice, simple option for setting exchange rates in GP.