Grouping products on invoices to reduce the length of a bill
Allowing to group the same products together on a bill would make it clearer for the guest. For example, if a guest stays for 15 days, his invoice will include 15 times the 'local tax' product making the invoice lengthy and not easy to read.
It would be better to simply display local tax x 15, for example.
It could maybe be set for specific products when configuring them.