Modify the main currency with correct converting in multistore/multicurrency mode

[larrson]

Hello,

I have two shops in mutistore mode.
Main currency of store 1 is Euro. It also offers the dollar as second currency.
Second store main currency is also Euro. And Polish zloty as second currency.
It works pretty much correctly (there is still a rounding problem, as the second currency doesn't have psychological prices but weird prices like 20.24 or 34.97).
But the real problem is this one : I want to change the main currency of shop B from euro to zloty. Since the prices are calculated from the main currency, and no matter what conversion I use, the price of a product will for example always be 10 regardless of the currency. This obviously is not what i need.
1-How can I change the main currency in a given store while keeping the right conversion to the Euro (base currency of my presta)?
2-How can i apply a decent rounding to the converted currency ?

has anyone managed to set up a real multi-currency environment. Thanks for reading.

I'm using Presta 1.7.6.5.

[larrson]

anyone ??