You can view your payout history and download a file for each payout containing a detailed, transaction-level report on your Seller Dashboard. Simply click on the menu icon on the top right (3 horizontal lines) and navigate to the "Payout" page, where you can export the document as a CSV and convert it to spreadsheet. The file contains a column for the BigCommerce order ID, which you can use to match with BigCommerce orders.
We don't provide monthly at the moment, but you can export daily reports. We're working on adding monthly support as well.