Issue/33352

app/code/Magento/Tax/Model/Calculation/UnitBaseCalculator.php

@@ -133,6 +133,7 @@ protected function calculateWithTaxNotInPrice(QuoteDetailsItemInterface $item, $
         $appliedRates = $this->calculationTool->getAppliedRates($taxRateRequest);
 
         $applyTaxAfterDiscount = $this->config->applyTaxAfterDiscount($this->storeId);
+        $applyTaxRounding = $this->config->applyTaxRounding($this->storeId);
         $discountAmount = $item->getDiscountAmount();
         $discountTaxCompensationAmount = 0;
 
@@ -164,14 +165,17 @@ protected function calculateWithTaxNotInPrice(QuoteDetailsItemInterface $item, $
                     false,
                     false
                 );
-                $unitTaxAfterDiscount = $this->roundAmount(
-                    $unitTaxAfterDiscount,
-                    $taxId,
-                    false,
-                    self::KEY_REGULAR_DELTA_ROUNDING,
-                    $round,
-                    $item
-                );
+
+                if ($applyTaxRounding) {
+                    $unitTaxAfterDiscount = $this->roundAmount(
+                        $unitTaxAfterDiscount,
+                        $taxId,
+                        false,
+                        self::KEY_REGULAR_DELTA_ROUNDING,
+                        $round,
+                        $item
+                    );
+                }
             }
             $appliedTaxes[$taxId] = $this->getAppliedTax(
                 $unitTaxAfterDiscount * $quantity,

app/code/Magento/Tax/Model/Config.php

@@ -43,6 +43,8 @@ class Config
 
     public const CONFIG_XML_PATH_APPLY_ON = 'tax/calculation/apply_tax_on';
 
+    public const CONFIG_XML_PATH_APPLY_TAX_ROUNDING = 'tax/calculation/apply_tax_rounding';
+
     public const CONFIG_XML_PATH_APPLY_AFTER_DISCOUNT = 'tax/calculation/apply_after_discount';
 
     public const CONFIG_XML_PATH_DISCOUNT_TAX = 'tax/calculation/discount_tax';
@@ -210,6 +212,21 @@ public function applyTaxAfterDiscount($store = null)
         );
     }
 
+    /**
+     * Get configuration setting "Apply Tax Rounding" value
+     *
+     * @param   null|string|bool|int|Store $store
+     * @return  bool
+     */
+    public function applyTaxRounding($store = null)
+    {
+        return (bool) $this->_scopeConfig->getValue(
+            self::CONFIG_XML_PATH_APPLY_TAX_ROUNDING,
+            \Magento\Store\Model\ScopeInterface::SCOPE_STORE,
+            $store
+        );
+    }
+
     /**
      * Get product price display type
      *  1 - Excluding tax

app/code/Magento/Tax/Test/Unit/Model/Calculation/UnitBaseCalculatorTest.php

@@ -182,6 +182,10 @@ public function testCalculateWithTaxNotInPrice()
             ->method('applyTaxAfterDiscount')
             ->willReturn(true);
 
+        $this->mockConfig->expects($this->once())
+            ->method('applyTaxRounding')
+            ->willReturn(true);
+
         $this->mockCalculationTool->expects($this->once())
             ->method('getRate')
             ->with($this->addressRateRequest)

app/code/Magento/Tax/Test/Unit/Model/ConfigTest.php

@@ -133,6 +133,12 @@ public function dataProviderScopeConfigMethods(): array
                 true,
                 true
             ],
+            [
+                'applyTaxRounding',
+                Config::CONFIG_XML_PATH_APPLY_TAX_ROUNDING,
+                true,
+                true
+            ],
             [
                 'getPriceDisplayType',
                 Config::CONFIG_XML_PATH_PRICE_DISPLAY_TYPE,

app/code/Magento/Tax/etc/adminhtml/system.xml

@@ -71,6 +71,11 @@
                     <source_model>Magento\Config\Model\Config\Source\Yesno</source_model>
                     <comment>When catalog price includes tax, enable this setting to fix the price no matter what the customer's tax rate.</comment>
                 </field>
+                <field id="apply_tax_rounding" translate="label comment" type="select" sortOrder="80" showInDefault="1" showInWebsite="1">
+                    <label>Apply Tax Rounding</label>
+                    <source_model>Magento\Config\Model\Config\Source\Yesno</source_model>
+                    <comment>When catalog price includes tax, enable this setting to round tax amount.</comment>
+                </field>
             </group>
             <group id="defaults" translate="label" sortOrder="30" showInDefault="1" showInWebsite="1" showInStore="1">
                 <label>Default Tax Destination Calculation</label>

app/code/Magento/Tax/etc/config.xml

@@ -21,6 +21,7 @@
                 <price_includes_tax>0</price_includes_tax>
                 <shipping_includes_tax>0</shipping_includes_tax>
                 <apply_tax_on>0</apply_tax_on>
+                <apply_tax_rounding>1</apply_tax_rounding>
             </calculation>
             <defaults>
                 <country>US</country>