Can I change how GnuCash calculates sales tax?

[Frank H. Ellenberger]

Hi all,

Am 01.04.2013 19:21, schrieb Derek Atkins:
> "R. Victor Klassen" <rvklassen at gmail.com> writes:
>
>> I've encountered the same thing, although I'm not even sure it is
>> always whether the tax calculation is per-item or on the total.
>>
>> I suspect that there are small numerical issues in the calculation -
>> and I'm not saying whose calculation, the merchant's or GnuCash's -
>> which lead to occasional inconsistencies in the calculation.  Things
>> like one using double precision floating point, while the other uses
>> whatever was built into some cash register years ago and is not being
>> emulated in whatever cash register they currently have.
>
> GnuCash uses rational numbers/fractions internally, and computes the tax
> on each item individually, adds up the tax on each item using full
> rationals, and then rounds the result to the currency.  This is why you
> can be off a penny.
>
>> Quickbooks calculated the sales tax, and autofilled a line that you
>> could then edit to correct it.  I've not seen the same in GnuCash.
>
> Patches always welcome, but doing this would be very hard given the way
> GnuCash works.  The tax amount isn't actually stored anywhere with the
> invoice, it's always computed.  Once you post it the tax is computed and
> split out, but when you display the invoice later it still re-computes
> the tax and doesn't look at the posted transaction.
>
>> Please remember to CC this list on all your replies.
>> You can do this by using Reply-To-List or Reply-All.
>
> -derek
>

We started a discussion some time ago. But there a still a bunch open 
questions.

So you are invited to read and comment on Bug 502853: Incorrect tax 
rounding in invoice (rounding of .5)
https://bugzilla.gnome.org/show_bug.cgi?id=502853

Frank