Section 735 ILCS 5/12-634 - Determining money of the claim(a) The money in which the parties to a transaction have agreed that payment is to be made is the proper money of the claim for payment.(b) If the parties to a transaction have not otherwise agreed, the proper money of the claim, as in each case may be appropriate, is the money: (1) regularly used between the parties as a matter of usage or course of dealing;(2) used at the time of a transaction in international trade, by trade usage or common practice, for valuing or settling transactions in the particular commodity or service involved; or(3) in which the loss was ultimately felt or will be incurred by the party claimant.