Help with AJAX code in tpl files.

While i can somehow understand how php code works and what it does with a bit of googling around, i'm totally stuck on several places where AJAX code is used. I want to use only one currency and to help people navigate i added display of second currency in shop. But i failed to change this partially in checkout/cart.tpl and couldn't add at all in checkout/checkout.tpl

Can anyone tell how to display second value with this kind of function? In picture below i could change totals, since they are populated by php and failed with shipping. I've already added changes to live shop, but would really like to fully complete this idea.