В таблице в колонке с суммой скидки должен быть такой код
<td>
<span>{l s='Up to'}</span>
{if $quantity_discount.price >= 0 || $quantity_discount.reduction_type == 'amount'}
{$discountPrice=$productPriceWithoutReduction|floatval-$quantity_discount.real_value|floatval}
{else}
{$discountPrice=$productPriceWithoutReduction|floatval-($productPriceWithoutReduction*$quantity_discount.reduction)|floatval}
{/if}
{$discountPrice=$discountPrice * $quantity_discount.quantity}
{$qtyProductPrice=$productPriceWithoutReduction|floatval * $quantity_discount.quantity}
{convertPrice price=$qtyProductPrice - $discountPrice}
</td>