Welcome to the forums,
Might have to file an RFE in
bugzilla for reverse alpha/numeric sort order toggling; or vote for
Bug 23532 - sorting the sequence of the mail folders
In the meantime could make a structure like this:
TechStuff
TechStuff\Ticket5
TechStuff\Ticket6
TechStuff\Closed
TechStuff\Closed\Ticket1
TechStuff\Closed\Ticket2
TechStuff\Closed\Ticket3
TechStuff\Closed\Ticket4
So that you can collapse the closed folder, but their still there for under:TechStuff searches.