how do I add to cart as I progress the orderform

I want customer to select options as they progress the order form

i.e.

Question : please select your preferred registered office:

London £50

Manchester £40

Glasgow £25

Once select the amount is then added to the cart

Questions : Do you require Mail Forwarding?

Yes - £90

No - £0

Once select the amount is then added to the cart

Unfortunately, there's no add cart system in our form builder.

You can setup products, subscriptions and custom amount but once form is submitted, it will redirect the user or pass the data on the payment processors that we support.

You can learn more how to setup an order form in this guide: http://www.jotform.com/help/165-Setting-Up-Your-First-Order-Form

If you wish to make a ecommerce store with the add cart function, you can check Shopify. May we know the payment integration you are using? If it is Paypal, perhaps we can send a feature request to our developers, if I am not mistaken, Paypal has an add cart function.