The integration with Quickbooks works by passing daily sales and cost of goods sold data to Quickbooks.

Sales get pushed to a receipt endpoint. The sales data is pushed based on this article:

For every tax present on the order, it adds a separate item to the sales receipt and attaches items referencing payment accounts to make

the total of the receipt $0.

The integration creates a separate Quickbooks account for every tax rate and payment method in POS.

To enable it, you need to enable 'Quickbooks integration' setting in General settings and link each location to a QB instance in Settings -> API keys & integration.

It'll start passing the data the next day after being linked.