This question is an exact duplicate of:
I am allowing user to apply some discount amount on cart page. When user clicks on checkbox or enter manually, it will call ajax action and display the discount amount in cart totals block as shown below.
How can I load cart totals block using ajax and show discounted amount, when user clicks on checkbox ?
Note: This question has been asked before, but as I still do not have an answer for it or some code flow, it compelled me to ask it again. You can still post some reference close to this question in terms of ajax with magento and container updaation.