diff --git a/includes/class-wc-cart-totals.php b/includes/class-wc-cart-totals.php
index 538977363f0..34f64c1f396 100644
--- a/includes/class-wc-cart-totals.php
+++ b/includes/class-wc-cart-totals.php
@@ -579,10 +579,28 @@ final class WC_Cart_Totals {
 				$taxes[ $rate_id ] += $this->round_line_tax( $rate );
 			}
 		}
+		$taxes = $this->round_merged_taxes( $taxes );
 
 		return $in_cents ? $taxes : wc_remove_number_precision_deep( $taxes );
 	}
 
+	/**
+	 * Round merged taxes.
+	 *
+	 * @since 3.4.5
+	 * @param array $taxes Taxes to round.
+	 * @return array
+	 */
+	protected function round_merged_taxes( $taxes ) {
+		if ( $this->round_at_subtotal() ) {
+			foreach ( $taxes as $rate_id => $tax ) {
+				$taxes[ $rate_id ] = wc_round_tax_total( $tax, 0 );
+			}
+		}
+
+		return $taxes;
+	}
+
 	/**
 	 * Combine item taxes into a single array, preserving keys.
 	 *