Commerce Multicurrency provides a way to improve the multicurrency capabilities of Drupal Commerce. It provides both a way to do live price synchronization between currencies by using exchange rate services or setting a fixed rate but also a "manual" mode where you get a field for each currency in order to set a different price per currency.

The module also provides rules integration so you can check, replace and alter currencies and prices depending on a given context and also great UI helpers such as a currency switcher block.

The exchange rate engine provides an API so you can plug to different servers to get updated currency exchange rates.