Hi,
The best I think is to edit the file "listing" of the view "product" via the menu Display>Views and add such code at the beginning:
<?php
$suffix = $this->pagination->hikaSuffix;
$this->pagination = hikashop_get('helper.pagination', $this->pageInfo->elements->total+$xxx, $this->pageInfo->limit->start, $this->pageInfo->limit->value);
$this->pagination->hikaSuffix = $suffix;
?>
where $xxx is a variable with the number that you want to add to the total.
This will reset the pagination system for the listing with a new total before the pagination gets displayed using it.