The ability to collect and correlate the required information for Australian invoice requirements as described here from the ATO https://www.ato.gov.au/business/gst/tax-invoices/
This requires collection of customer ABN and being able to print such on invoice with a separate line item for GST. The words "Tax Invoice" on top of receipt, Our ABN under our business name and the words "Total price includes GST" next to total. This is Min legal req. for sales over $1000 in AUS