I am not sure if this will work for your site, but if you want to NOT set a Product Price and just use the Qty Discounts, you could use your templates and overrides for:
/includes/templates/template_default/templates/tpl_modules_products_quantity_discounts.php
and copy that, if not already dones, to:
/includes/templates/template_default/your_templates_dir/tpl_modules_products_quantity_discounts.php
and then add the code in RED:
Code:
<tr>
<?php
if ($show_qty != 1) {
?>
<td align="center"><?php echo $show_qty . '<br />' . $currencies->display_price($show_price, zen_get_tax_rate($products_tax_class_id)); ?></td>
<?php
}
?>
<?php
foreach($quantityDiscounts as $key=>$quantityDiscount) {
?>
<td align="center"><?php echo $quantityDiscount['show_qty'] . '<br />' . $currencies->display_price($quantityDiscount['discounted_price'], zen_get_tax_rate($products_tax_class_id)); ?></td>