Subscription Billing already priced usage

Dear SAP Experts,

a customer of us would like to know if it is possible to transfer already priced usage into Subscription Billing? The usage comes from a gas station and would include taxes too.

As we have found no field in the APIs to include the price, our solution would be to send the usage directly to SAP CI as billable items including tax amount.

Can you please confirm this or suggest another solution?

Thank you a lot in advance!

Best regards

Norbert Sarfi