Currency rate issue (decimal number)

Hello guys,
I have a little issue here with your multi currency plugin. I set up the main currency of the store in Rubles (for pricing managment purposes), and I just figured out that your system update the currencies only with 2 decimals.

For example, on the settings of your plugin right now: 1Rub=0.02€
But in facts it is: 1Rub:0.01615€

So for these low valued currencies, the final difference in price conversion is pretty high! Can you fix that please? It would be very very usefull.

Thanks in advance!