ricardo.ch platform supports ONLY CHF (Swiss Franc) and we target the Swiss Market at the moment.
For this reason, your Magento shop should have as base currency CHF.
The version 1.0 of the extension doesn't support price conversion.
You have two solutions
- If your shop doesn't have the base currency CHF, use the currency conversion of Magento available from the version 1.1. More information about this topic in our PDF Document
- Otherwise, you have to create an additional Website in Magento backend and set the base currency to CHF. It's actually the best solution to have exactly what you expect regarding price rounding and so on.