I would suggest that you devise an abbreviation for these shapes and describe their function in a transcriber's note. I believe you could use [simbraille]$k$sa][/simbraille] for the first shape (calculator key, shade above for linear inequality) and [simbraille]$k$sb][/simbraille] for the second shape (calculator key, shade below for linear inequality).
Ideally, you should provide a tactile representation of these shapes, either within your TN or in preliminary pages.
Please see the portion of the 2007 update to the Nemeth Code that deals with section 111.d (calculator keys) as well as section 107 of the Nemeth Code. edited by Kyle Transcriber on 7/6/2015