How can we specify currency when inserting a record in Invoices module?

How can we specify currency when inserting a record in Invoices module?

We are using upsert record API to add a record in the Invoices module using the V2 API. But the record is added as the USD currency and not as GBP.

The Home Currency is setup as GBP. Documentation dosen't specify any attribute to use as currency.

Is is possible to use currency code in the API?