fix(taxes): increase rounding threshold for tax breakup calculations

(cherry picked from commit 7f87a5e5c6)

erpnext/controllers/taxes_and_totals.py

@@ -522,7 +522,7 @@ class calculate_taxes_and_totals:
 			diff = flt(expected_amount - actual_breakup, 5)
 
 			# TODO: fix rounding difference issues
-			if abs(diff) <= 0.5:
+			if abs(diff) <= 1:
 				detail_row = self.doc._item_wise_tax_details[last_idx]
 				detail_row["amount"] = flt(detail_row["amount"] + diff, 5)
 

erpnext/controllers/tests/test_item_wise_tax_details.py

@@ -124,3 +124,107 @@ class TestTaxesAndTotals(ERPNextTestSuite):
 		]
 
 		self.assertEqual(actual_values, expected_values)
+
+	def test_item_wise_tax_detail_with_multi_currency(self):
+		"""
+		For multi-item, multi-currency invoices, item-wise tax breakup should
+		still reconcile with base tax totals.
+		"""
+		doc = frappe.get_doc(
+			{
+				"doctype": "Sales Invoice",
+				"customer": "_Test Customer",
+				"company": "_Test Company",
+				"currency": "USD",
+				"debit_to": "_Test Receivable USD - _TC",
+				"conversion_rate": 129.99,
+				"items": [
+					{
+						"item_code": "_Test Item",
+						"qty": 1,
+						"rate": 47.41,
+						"income_account": "Sales - _TC",
+						"expense_account": "Cost of Goods Sold - _TC",
+						"cost_center": "_Test Cost Center - _TC",
+					},
+					{
+						"item_code": "_Test Item",
+						"qty": 2,
+						"rate": 33.33,
+						"income_account": "Sales - _TC",
+						"expense_account": "Cost of Goods Sold - _TC",
+						"cost_center": "_Test Cost Center - _TC",
+					},
+				],
+				"taxes": [
+					{
+						"charge_type": "On Net Total",
+						"account_head": "_Test Account VAT - _TC",
+						"cost_center": "_Test Cost Center - _TC",
+						"description": "VAT",
+						"rate": 16,
+					},
+					{
+						"charge_type": "On Previous Row Amount",
+						"account_head": "_Test Account Service Tax - _TC",
+						"cost_center": "_Test Cost Center - _TC",
+						"description": "Service Tax",
+						"rate": 10,
+						"row_id": 1,
+					},
+				],
+			}
+		)
+		doc.save()
+
+		details_by_tax = {}
+		for detail in doc.item_wise_tax_details:
+			bucket = details_by_tax.setdefault(detail.tax_row, {"amount": 0.0, "taxable_amount": 0.0})
+			bucket["amount"] += detail.amount
+
+		for tax in doc.taxes:
+			detail_totals = details_by_tax[tax.name]
+			self.assertAlmostEqual(
+				detail_totals["amount"], tax.base_tax_amount_after_discount_amount, places=2
+			)
+
+	def test_item_wise_tax_detail_with_multi_currency_with_single_item(self):
+		"""
+		When the tax amount (in transaction currency) has more decimals than
+		the field precision, rounding must happen *before* multiplying by
+		conversion_rate — the same order used by _set_in_company_currency.
+		"""
+		doc = frappe.get_doc(
+			{
+				"doctype": "Sales Invoice",
+				"customer": "_Test Customer",
+				"company": "_Test Company",
+				"currency": "USD",
+				"debit_to": "_Test Receivable USD - _TC",
+				"conversion_rate": 129.99,
+				"items": [
+					{
+						"item_code": "_Test Item",
+						"qty": 1,
+						"rate": 47.41,
+						"income_account": "Sales - _TC",
+						"expense_account": "Cost of Goods Sold - _TC",
+						"cost_center": "_Test Cost Center - _TC",
+					}
+				],
+				"taxes": [
+					{
+						"charge_type": "On Net Total",
+						"account_head": "_Test Account VAT - _TC",
+						"cost_center": "_Test Cost Center - _TC",
+						"description": "VAT",
+						"rate": 16,
+					},
+				],
+			}
+		)
+		doc.save()
+
+		tax = doc.taxes[0]
+		detail = doc.item_wise_tax_details[0]
+		self.assertEqual(detail.amount, tax.base_tax_amount_after_discount_amount)