[16.0][ADD] account_tax_round_down

[yostashiro]

This module provides the function of rounding down the tax amount in invoices (and also
other business documents such as sales orders and purchase orders).

By default, Odoo uses the "HALF-UP" method to round tax amounts. However, in some
regions, such as Japan, some industries have a common practice of rounding down instead.
This module accommodates such local conventions by offering an alternate rounding method.

@qrtl QT4986

[yostashiro]

There seems to be a happy-new-year error in a test from account_fiscal_year_auto_create, which I think will be cleared if I push again tomorrow.

2024-12-31 17:38:47,994 929 ERROR odoo odoo.addons.account_fiscal_year_auto_create.tests.test_module: FAIL: TestModule.test_cron
Traceback (most recent call last):
  File "/__w/account-financial-tools/account-financial-tools/account_fiscal_year_auto_create/tests/test_module.py", line 52, in test_cron
    self.assertFalse(new_fiscal_year)
AssertionError: account.fiscal.year(5,) is not false

This line seems to be an issue: https://github.com/OCA/account-financial-tools/blob/2ae3d17/account_fiscal_year_auto_create/models/account_fiscal_year.py#L24

CC: @legalsylvain

[yostashiro]

I was wondering if there is any real need in the community outside Japan for rounding down calculated tax amounts. If not, I might just include this module in the l10n-japan repo instead. Your comments are welcome.

[kanda999]

Code check and functional review.