In QB item list, there is no tax item applied to the group. Also in the item list, each item has a "G" tax code (GST only). However, when I select the group for an invoice in QB, the grouped item name is shown, and then the items are shown with the correct tax code for the customer (in this case, "H").
In Method, the group name is assigned a tax code of "E" (employee?) and the discount portion has a tax code of "S" (sales discount), while each item has a "G". This is not overwritten by the customer's tax code, which is "H" - even after submitting and processing in QB.