I'm unsure as to whether or not the sector size is queryable, but if it is I think there should be an option (or defaulted) display of the actual size on disk of the files deleted, since it more accurately represents the size of files deleted in large numbers (such as temporary internet files or the new mozilla cache architecture)
Good thing there's a C++ function that does exactly this: http://msdn.microsoft.com/en-us/library/windows/desktop/aa364930%28v=vs.85%29.aspx