when I use the Consumption usage details API I am getting usage cost details day wise. I saw that azure uses USD for billing and show invoices in the customer's local currency link so that How exchange rates are selected for this case (whether previous day rate or at the time rate or previous month rate) and which exchange rate will be used for the invoice.
During invoice, whether the same exchange rate will be applied to all daily split up bills or exchange rates are chosen as per usage date.