Live answer from a working API, not written from memory.
Flat 10% GST applies to digital services supplied to Australian consumers.
curl "https://checkout-tax-api.pages.dev/rate?country=AU&product_type=digital"
EU-27 + UK VAT, US state sales tax, Canada GST/HST/PST and Australia GST, with the reverse-charge decision logic, are all in it. It also ships as a one-time $49 self-host kit — full source, tests, and a one-command deploy to your own Cloudflare Worker. The hosted API is free either way.