nuevo addon para calcular el precio con descuento antes del impuesto cuando se funciona con precios B2C, es una diferencia de un céntimo en cada línea, pero hay contables quisquillosos.

Sobreescribe compute_all de sale.order.line, seguramente cause problemas si se usan más addons que toquen el descuento.

sale_calc_discount_b2c/__init__.py

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+from . import models

sale_calc_discount_b2c/__manifest__.py

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+# Copyright 2021 Criptomart
+# License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl).
+{
+    'name': 'Sale Calc Discount B2C',
+    'summary': 'When prices are tax included, calculates the discount in price excluding tax.',
+    'version': '12.0.1.0.0',
+    'author': 'Criptomart',
+    'depends': [
+        'sale',
+     ],
+    'installable': True,
+    'auto_install': False,
+    'application': False,
+}

sale_calc_discount_b2c/models/__init__.py

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+from . import sale

sale_calc_discount_b2c/models/sale.py

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+# Copyright (C) 2021: Criptomart (<https://criptomart.net/>)
+# @author: Criptomart (<tech@criptomart.net>)
+# License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl.html).
+
+#import logging
+
+from odoo import models, fields, api
+
+#_logger = logging.getLogger(__name__)
+
+class SaleOrderOrderLine(models.Model):
+    _inherit = 'sale.order.line'
+
+    @api.depends('product_uom_qty', 'discount', 'price_unit', 'tax_id')
+    def _compute_amount(self):
+        """
+        Compute the amounts of the SO line.
+        """
+        for line in self:
+
+          price = line.price_unit
+          taxes = line.tax_id.compute_all(price, line.order_id.currency_id, line.product_uom_qty, product=line.product_id, partner=line.order_id.partner_shipping_id)
+          if  line.discount:
+             price_disc = taxes['total_excluded'] * (1 - (line.discount or 0.0) / 100.0)
+             ctx = dict(self.env.context, force_price_include=False)
+             taxes = line.tax_id.with_context(ctx).compute_all(price_disc, line.order_id.currency_id, line.product_uom_qty, product=line.product_id, partner=line.order_id.partner_shipping_id)
+
+          line.update({
+                'price_tax': sum(t.get('amount', 0.0) for t in taxes.get('taxes', [])),
+                'price_total': taxes['total_included'],
+                'price_subtotal': taxes['total_excluded'],
+          })