@DG925 At this time you can organize your open tickets by name which is alphabetical -- but also by the amount and time if that helps? To see these options click Tickets > and click the sort icon (two arrows).
You can also use the search box to enter your guest's last name pull up an open tab. Can you share a bit more about why sorting the tabs by last name this would be helpful to you? Is it an easier way to find a guest you know will be at the end of the list?