You can enable the currency exchange rates API in Catalog Settings > Currency Switcher:
If you check the Auto Update Currency Rates checkbox, it will daily connect to the implecode.com to automatically update your currency exchange rates.
You can also manually refresh the exchange rates with the Refresh All Exchange Rates button.
Adjust the synced exchange rates
You can enter a positive or negative percentage in the Currency Rate Modificator input if you want to adjust the downloaded exchange rates automatically.
The exchange rates API works only with an active license for the Currency Switcher extension.