Can I change how GnuCash calculates sales tax?

[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

-- 
       Derek Atkins, SB '93 MIT EE, SM '95 MIT Media Laboratory
       Member, MIT Student Information Processing Board  (SIPB)
       URL: http://web.mit.edu/warlord/    PP-ASEL-IA     N1NWH
       warlord at MIT.EDU                        PGP key available