Try this...
{if $product.taxed_price gt 0 and $product.list_price gt 0}
<td align="right" valign="top" width="60" id="save_percent_box"{if $product.taxed_price >= $product.list_price} style="display: none;"{/if}>
{if $discount gt 0}
<table width="60" cellspacing="1" cellpadding="2">
<tr>
<td class="SaveMoneyLabel">
<br />
{math equation="100-(price/lprice)*100" price=$product.taxed_price lprice=$product.list_price format="%3.0f" assign=discount}
<span id="save_percent">{ $discount }</span>% </td>
</tr>
</table>{/if} </td>
{/if}