Your data is less complicated than the one in the fiddle example. You have 1 model that contains a collection. From my experience this calls for a combination of CompositeView + ItemView for each collection member.
<script id="invoice-template" type="text/template">
<%= name %> on <%= date %>:
<ul></ul>
</script>
<script id="billing-template" type="text/template">
<%= date %>, <%= totalAmount %>$ for product: <%= product %>
</script>
var BillingView = Backbone.Marionette.ItemView.extend({
template: "#billing-template",
tagName: "li"
});
var InvoiceView = Backbone.Marionette.CompositeView.extend({
template: "#invoice-template",
tagName: "ul",
itemView: BillingView
});
See here it in action: http://jsfiddle.net/xX9X3/116/