The class for this block is defined in the file Mage/Checkout/Block/Cart/Totals.php
If you open this file you will find renderTotals() defined here. I think you are interested in making changes here. If yes, you can override this class and make your changes. 

How to find the files in magento directory


Larger view of the issue is here: http://i1268.photobucket.com/albums/jj572/LinuxOwner/question.png
