How to Setup Approval Amount in Certain Currency Through Workflow?

Hi expert,

i have PO approval condition as follow:

-Base currency of company is in IDR, all of foreign currency exchange rates will be multiply to IDR

-Approval limit PO is in USD, for all currencies.

-Level limit amount in USD: $ 1 - $ 100.000 will be approved by user A

-Level limit amount in USD: more than $100.000 will be approved by user B

let say, user creates PO in JPY 1.000, user wants system run approval workflow should be met the amount limit amount in USD based on parameter above. the purpose is system should convert JPY to USD to get USD amount.