Grand total not update automatically Magento 1.9

Well, I created a discount coupon. When I use the coupon code, this is applied perfectly, but the Grand Total not update until refresh the page.

The Ajax execute perfectly and the response is correct. See the next img.

With the code applied, before refresh the page. enter image description here

With the code applied, after refresh the page. enter image description here

In here cancel the coupon and not update the Grand Total, but disapear the discount. enter image description here

See the reviewAction response. The amount in the response is not the same as in the total shown.

Where is the issue? thanks in advance.

PD: My store is in Spanish.

Changelog generation, manually or automatically? What is recommended?

I was reading what is a changelog in keepachangelog.com and says that we shouldn’t drop our git logs for the creationg of this file, but I see a lot of projects do it like the Angular framework repository, so I am wondering what is the recommended strategy for doing this, what kind of users are we aiming for or the special cases in which we would like to drop our git logs in this file instead of writing it down ourselves.

I want to point out that I am new to this type of workflow as the company I am currently working for never used a changelog and VCS and I am trying to organize better the projects we develop.