The x-cart support help desk provided the answer for me so I thought I would share it here. This code was written to supply a gift certificate subtotal and answers my question.
Code:
{if $cart.giftcerts ne ""}
{assign var="gc_summary_subtotal" value=0}
{section name=giftcert loop=$cart.giftcerts}
{if $cart.giftcerts[giftcert].deleted eq ""}
{assign var="have_giftcerts" value="Y"}
{math equation="x+y" x=$gc_summary_subtotal y=$cart.giftcerts[giftcert].amount assign="gc_summary_subtotal"}
{/if}
{/section}
{if $have_giftcerts eq "Y"}
GiftCertificates Subtotal: {include file="currency.tpl" value=$gc_summary_subtotal}
{/if}
{/if}