We have a situation where the price of items in the cart can change depending on the user credentials. For example, logged-in users pay less than guest users. Consider the case where user added item 1 on cart as guest (with full price), then logged in, and then added item 2 in cart for which a discount was applied. Now at the time of checkout, we need to do a final validation and correct the price to ensure that discounts are applied uniformly to all the items in cart. I think one can use jQuery callbacks to do this, but I am not sure if my understanding is correct. Can one change the cart price at the time of checkout by resupplying the details of items that are already in cart?