Currency issues on internal req / internal sales order

We want to use internal requisitions and internal sales orders to transfer material between Org U, which uses US dollars, and Org C, which uses Canadian dollars.  There seems to be a currency issue, however.  How can we correct this?

Currency conversion rate:   1 CAD = 0.80 USD

If a part costing 100 CAD is sent from Canada to the US, then the part cost in the US is 80 USD, which is correct.

If a part costing 100 USD is sent from the US to Canada, then the part cost in Canada is 80 CAD, which is wrong.  It should be 100 / 0.80 = 125 CAD.

Are there any settings we can check related to currency?  Is anyone else successfully doing internal requisitions / internal sales orders between organizations that use different currencies?