If the contract is "denominated in eruos," then the values written into the contract are in euros. However, this sentence is saying that the actual amounts of money involved, perhaps in the associated invoices, are (to be) adjusted to compensate for changes in the exchange rate to dollars.
I see no reason to expect that the invoices will be in dollars -- just that they will not be identical to the amounts in the contract. Since (currently) the dollar has lost significant value (say 40%) against the euro, I would expect to see invoices to American customers for 40% less than the contract says (in euros) so that he pays the same in dollars as he would have before the currency fall. Similarly, if the money is to be paid to an American supplier, then I would expect him to receive 40% less (in euros) than the contract says.
(before anyone complains, I know that the arithmetic isn't quite right. It serves for the purpose of illustration!)
Edit: by the way, thanks is spelled with "ks," not with "x."