[sale_tax_include][account_tax_include] rounding error on taxed amount

Hello Sebastien,

Are you sure this happens at your end?

I made Invoice and SO with the same configuration: I get 7.53,1.47 and 9.00.

Can you recheck? I checked with price_accuracy 2 3 4 too.

Thanks.

Hello Jay,

I'm sorry, the bug report of Sebastien was incomplete indeed.
Watch carefully the described steps but also do the following:
The rounding bug will ONLY occurs
- IF your tax is set with the flag "Tax included in price" right on the tax object (not just on the order/invoice line)
- AND if you choose the order/invoice method as "Tax excluded" (it will be included anyway due to the tax setting)
use a unit price with 9 EUR and a sale VAT at 19.6% to make sure you'll see 9.01 EUR as the line subtotal.

For now there is that simple rounding issue to fix.

But yes, in the long run, this is awkward functionally speaking: once you parameter a tax to be included in price at the tax level, the order/invoice select box Tax excluded/Tax included is just useless except this will make that rounding bug show or not!

My view is that this option should be removed (as it is just less fined grained) from the order/invoice form and it should be re-factored into the core of OpenERP (so many accounting require included taxes) avoiding thus those brittle brutal override that do not call super and are thus very easily incompatible between modules and would generate an endless series of bugs. I think 5.2 is the opportunity to bite the bullet, I can't imagine this being all broken with broken modules on the top of it developing until mid 2011 if 5.2 is missed.

If you like you can read my comment and comment on the accounting expert list here:
https://launchpad.net/~openerp-expert-accounting
archive: http://n3.nabble.com/More-fun-with-taxes-included-and-rounding-issues-tc140823.html#a140823

Certainly, the tax calculations should have all decimals in its computation and at the end the roundup.

To achieve the total tax computation I have made the following changes:

1-In the database, table account_invoice_line I have modified the fields to store currencies to be numeric(16,8). I use eight decimals because PostgreSQL uses two bytes for every group of four decimals so I am able to see the real numbers.

2-Started the openerp-server with parameter: --price_accuracy=5.

3-Modified the source code for line tax and sum calculation with straight double precision since the roundup to currency precision should be made only at the end. I have attached the patch just in case you want to test.

I am aware that there is an effort to put-in some criteria on currency, price and computing calculation's precision for the next version to come (https://launchpad.net/~openerp-expert-accounting.)

There should be a more precise and close look to rounding of calculations, but this patch has helped me to achieve precise tax calculations of invoices for products with small values and many lines, that otherwise could lead to round per line to one cent or even to zero! so tax calculation is wrongly calculated.

I see it like -maybe- is not a coding bug itself but -maybe- a conceptual gap that looks like a bug; never-the-less the result is wrong. Good luck guys!

Can you check with the trunk version?
Price_accuracy has been fixed with trunk version.
Thanks.

Any progress on this to include the patch in version 5?

Won't fix: we rewrite everything in the trunk branch so that the sale_ta_include and account_tax_include modules are not usefull anymore. Everything is tax include/excluded by default in trunk according to the configuration of the taxes.