How can I call an Umbraco Surface controller action method from an jQuery ajax call?

Currently,

In my razor templates, if I have an jQuery ajax call, I am calling passing the following to my url parameter:

/umbraco/Surface/ProcessCheckoutOrder/Checkout

How can I call this from the ajax method without having to specify:

/umbraco/Surface/

This is a companion discussion topic for the original entry at https://our.umbraco.com/forum/74493-how-can-i-call-an-umbraco-surface-controller-action-method-from-an-jquery-ajax-call