Reported for: WooCommerce Multilingual 3.4.3
Resolved in: WooCommerce 2.3
If the default currency is configured to display more decimals than the other currencies, the prices in the secondary currencies would be approximated to the number of decimals that they have more.
The wc_price function allows one to specify a custom currency and display a price in a separate currency than the default one. With the current filters in WooCommerce it’s not possible to detect when a custom currency is provided thus the price format can be set according to the new custom currency provided. The price format defined for the default currency is used.
The is no workaround at the moment.
This will not be an issue when using the upcoming WooCommerce 2.3 version. This version includes the right filters that are needed for the price conversion to work correctly.