TaxCloud needs to receive a "Capture" API call so we know which items in the shopping cart have been purchased.
When items are placed in a shopping cart, TaxCloud receives a Lookup API call to determine the amount of sales tax to include with the order. Then, when the customer is ready to buy the items you must send TaxCloud an Authorize API call and a Capture API call.
The Authorize API call confirms that the customer has paid for the item(s). The Capture API call confirms that the item(s) have been shipped. Please be aware that you can combine these two API calls into one API call using "AuthorizeWithCapture".
Note: If you permit customers to apply coupons or discounts to their order once items have been placed in the shopping cart, be sure to send TaxCloud another Lookup API call after the discount has been applied.