[myshop]

Thanks for your help, however I cannot see how any of the settings would introduce a calculation error like this?

I have it set so that product prices include tax.

So if a product is $11.00 this is made up from $10.00 ex tax price + 10% ($1.00) = 11.00.
So the GST/TAX component of 11.00 is $1.00 - not $1.10.

This is a basic arithmetic error? unless im missing something?

Note: Just updated cart to latest 5.2.14 - same problem