wip

app/Concerns/ManagesLineItems.php

     protected function updateLineItemTotals(DocumentLineItem $lineItem, DocumentDiscountMethod $discountMethod): void
     {
         $lineItem->updateQuietly([
-            'tax_total' => $lineItem->calculateTaxTotal()->getAmount(),
+            'tax_total' => $lineItem->calculateTaxTotalAmount(),
             'discount_total' => $discountMethod->isPerLineItem()
-                ? $lineItem->calculateDiscountTotal()->getAmount()
+                ? $lineItem->calculateDiscountTotalAmount()
                 : 0,
         ]);
     }

app/Utilities/RateCalculator.php

 
     public static function calculatePercentage(int $value, int $scaledRate): int
     {
-        return (int) round(($value * $scaledRate) / self::PERCENTAGE_SCALING_FACTOR);
+        $result = ($value * $scaledRate) / self::PERCENTAGE_SCALING_FACTOR;
+
+        return (int) round($result, 0, PHP_ROUND_HALF_EVEN);
     }
 
     public static function scaledRateToDecimal(int $scaledRate): float

database/factories/Accounting/DocumentLineItemFactory.php

 
                 $lineItem->refresh();
 
-                $taxTotal = $lineItem->calculateTaxTotal()->getAmount();
-                $discountTotal = $lineItem->calculateDiscountTotal()->getAmount();
+                $taxTotal = $lineItem->calculateTaxTotalAmount();
+                $discountTotal = $lineItem->calculateDiscountTotalAmount();
 
                 $lineItem->updateQuietly([
                     'tax_total' => $taxTotal,
 
                 $lineItem->refresh();
 
-                $taxTotal = $lineItem->calculateTaxTotal()->getAmount();
-                $discountTotal = $lineItem->calculateDiscountTotal()->getAmount();
+                $taxTotal = $lineItem->calculateTaxTotalAmount();
+                $discountTotal = $lineItem->calculateDiscountTotalAmount();
 
                 $lineItem->updateQuietly([
                     'tax_total' => $taxTotal,
 
                 $lineItem->refresh();
 
-                $taxTotal = $lineItem->calculateTaxTotal()->getAmount();
-                $discountTotal = $lineItem->calculateDiscountTotal()->getAmount();
+                $taxTotal = $lineItem->calculateTaxTotalAmount();
+                $discountTotal = $lineItem->calculateDiscountTotalAmount();
 
                 $lineItem->updateQuietly([
                     'tax_total' => $taxTotal,