If the value isn't getting stored in the repository, that means you probably checked the "read-only" checkbox for the field in the form designer. You need to uncheck that. It not only makes the field read-only, it also adds the disabled attribute to it, which prevents the value from being submitted.

The following should help for your use case:

$(document).on("ready", function() {
    $(".total input").attr("readonly", true);
    $(".total input").val("your value");
});

You can use that in all scenarios where the user shouldn't be able to edit the value, but the value itself should get submitted.