Invoices Are Not Created
Invoices are not created within Rerun and sent over to your accounting software. Rerun also doesn't have the ability to pay open invoices from your accounting software. When you run a transaction in Rerun and sync it over to Xero, it will create a paid sales receipt in your accounting solution for the specific customer(s) that you ran the transaction(s) for.
When you're finished running the transactions for the day, click the "Sync" button found on the bottom of all Rerun tabs. This will sync all of your payments for that time frame over to your accounting software.
Please Note: Make sure you are set up with your accounting software by going to the Setup Assistant in the top right drop-down under "Welcome, your name", or go to the Settings tab > Sync.