Typical ecommerce workflow

When your customer opens a shopping cart and puts an item in it, call the ATE CreateTransaction API with and set AvataxTransactionType to SalesOrder. This will return a tax calculation based on your shipping address and the customer’s destination address, but it won't record a permanent transaction. You won’t have to do any cleanup for abandoned carts.
When the customer finalizes the order, call CreateTransaction again with AvataxTransactionType set to SalesInvoice.
When your order ships, call the CommitTransaction API to mark the transaction as committed. This will prevent accidental changes to the transaction and allow you to include it in a Managed Returns Services tax session.