There is an internal api in the IE libraries that controls clearing of
the 'Internet Cache'....
there are two... one for 'normal' integrity processes (64 bit tab processes
and ActiveX (flash)), another for low integrity processes (32 bit tab
processes and ActiveX (flash))
Use GPO (Start>Run>gpedit.msc) to configure user profiles on a domain
network to empty the TIF(s) on exit from the browser.
For computers on a public access network (library workstations), you can
default to inPrivate Mode from a desktop or Taskbar link
which does not retain any personally identifiable data of the user in
history, or cookies or flash cookies.....
questions about GPO management of IE should be posted to the TechNet
support forum for IE.