Add Maintenance and support cost to paypal page

See more:

HTML

web_development

I have an item which is available with and without Maintenance and support cost. Maintenance and support cost will depends on total number of items. I need to charge Maintenance and support cost along with the total cost. Is there any HTML variable in paypal checkout page where I can set this cost?

I'm using following sample code to create paypal page:

<form action="https://www.paypal.com/cgi-bin/webscr" method="post">
 <input type="hidden" name="cmd" value="_xclick">
 <input type="hidden" name="business" value="seller_id">
 <input type="hidden" name="item_name"  value="My item name">
 <input type="hidden" name="item_number" value="My item number">
 <input type="hidden" name="amount" value="1.00">
 <input type="hidden" name="currency_code" value="USD">
 <input type="submit" value="Buy now">
</form>

Any help is greatly appreciated.
Regards,
Anshh