We are using the terminal API to perform sales on the terminal. Everything is working fine except when logging into Square the sales don’t have any tax component (GST) applied. Is this something that needs to be set via the API when doing the sale or a setting in Square?
Are you passing in an order_id when calling CreateTerminalCheckout? If your only passing an amount all payments will show as a custom amount. 
Do you have examples of using orders within the context of a point of sale application, where every transaction is performed is different and immediate.
This is what we are following.
Yeah, our Orders documentation covers how to crate itemized orders that include taxes for payments.
Also where are you processing payments? If it’s outside of the US orders aren’t supported and inclusive taxes aren’t currently available with Terminal API.
We are in Australia, so that is a problem. Any timeframe when this will be available outside the US?
Unfortunately we don’t have a public roadmap for features releases like this.
Ok, that’s disappointing as it really makes the Terminal API not usable for countries that have a sales tax.
You can still use it in countries that have sales tax. Any additional reporting for taxes would need to handled either by a tax professional or accounting integration.
The problem is then with other integrations, like into the Xero accounting system, will put the wrong amounts into Xero, with no tax applied, so every transaction needs to be manually adjusted in Xero. A time consuming process.
So this feature https://squareup.com/help/au/en/article/5237-xero-and-square is basically incompatible with the Square API.
Have you reached out to Xero about this? They may have a way to handle custom amounts. Cause payments from our 1st party products can be a custom amount too if their not itemized.