It is not often that I post a solution that is intended to be used in Iceland only. Here is one.
Arion Banki is one of the major national banks in Iceland and they want to support Dynamics NAV users. On their website you will find the currency exchange rates for every working date. I created an importer that will download the exchange rate from their website and import into NAV.
There are two ways to do this. First is to go into Currencies in the NAV Client and click on Import
The other way is to add a Job Queue Entry to make this an automatic task.
The process will find the last date imported into your system and import all days from and including that date to the current working date.