This depends on which payment method you have chosen to receive your commission payments.

PayPal Payments
If you have chosen to be paid by PayPal, your commission payments will be made in US Dollars [as they are displayed in your control panel].
If US Dollars is not your native currency - Check your paypal payment settings to see whether your payment is automatically converted to your native currency.

Store Credit Payments
If you have chosen to have your commission payments converted to store credit, this store credit will be created in the most geographically appropriate store for you to use and in the currency that store uses.
For example: If you live in the UK your store credit will be created in the UK store in GB Pounds.
                   If you live in Australia, your store credit will be created in the Australia store in AUS Dollars