Invoice GST 10% calculation method

I’m not sure if I am doing something wrong for some reason whenever I create an invoice and select 10% GST the total is slightly out.

For example I have just created an invoice which is for $284.90, I select the GST 10% which shows up as $25.90. But 10% of $284.90 would be $28.49.

Is there anyway to manually change how much GST is paid, so that my invoices matches my customers purchase orders?

Or have I done something incorrectly?

Is $284.90 tax-inclusive amount or you need to charge GST on top of that?

10% GST on $284.90 tax-inclusive amount is exactly $25.90.

Have a look at Wikipedia which explains this concept: Tax rate - Wikipedia

Manager doesn’t allow to override tax amounts. I just don’t see any valid use-case where this would be useful. When people want to override tax amounts, they are usually doing something wrong and you certainly don’t want to do mistakes when it comes to taxes. For tax office, it’s very easy to see that your tax paid and tax collected amounts are not the right proportion to your taxable sales and purchases. Those are usually triggers which initiate tax audits.

Thanks for the reply, $284.90 is tax inclusive