How to add currency exchange into model

[#1]

Could You please advice me what are good practices to apply currences into model?

Should I somehow add separate table (and do calculations directly invisual design?) or add calculated amounts in proper currency to each table?

Below I attach an example. I do have two fact tables, in each there are few facts: Spare parts cost, Labour cost, Invoice cost and claimed cost, accepted cost, cost of purchase. Claims are in different currencies (fe. EUR, USD, NOK, PLN) and I have to convert them all into PLN. I have to take into account the Repair_date as a date of exchange.

Maybe I should create Currency key and some foreign key like Currency & Date = Currency_claim & Repair date, but what next?

Will be grateful for Your help.