How to update checkout order totals?

Question

I just need some direction, please… I feel lost.

Basically I'm using Magento 1.7 & I’m working on a module that gives a customer an option to add gift wrapping during the onepage checkout process. I’m up to the point where I need to change the checkout total to reflect the change in price (and of course I would like to do this the right way.)

Looking at the frontend, I want to change this (under Order Review):

Subtotal $54.00
Shipping & Handling (Flat Rate - Fixed) $20.00
Grand Total $74.00

To this:

Subtotal $54.00
Gift Wrap $5.00
Shipping & Handling (Flat Rate - Fixed) $20.00
Grand Total $79.00 

Answer 1

The following link will hopefully guide into the right direction. It explains how to create a custom total: http://excellencemagentoblog.com/magento-add-fee-discount-order-total