CodeIgniter minor website addition. (TastyIgniter)

Looking for someone that is experienced with CodeIgniter and preferably familiar with TastyIgniter ([login to view URL]). I am looking to add a Tipping feature to the checkout cart. 1) Tip option in both delivery and pick-up checkout (attachment) . 1.a) Ability to remove the tip (similar to the coupon x). 1.b) Success message for both adding and removing the tip. 1.c) Tip (percentage) is added based on sub total. 2) Tip saved to the order database (same way the coupon/tax/total/etc is shown on the admin panel). 2.a) Tip should be displayed both on admin end and user end. 3) More detailed information of whats listed above will be provided.