The § symbol is used to define the currency. The § symbol appears in place of $ when typed within the game when using a standard keyboard.
A simolean is presumably made up of 100 'somethings' but I do not believe that the fraction has ever been given a name. Simcent or Simolette perhaps?
Woohoo I just got §564 for a large supreme pizza.
It is, perhaps, a reference to a Neal Stephenson short story, The Great Simoleon Caper, in which an online currency is developed called the Simoleon for use in "the Metaverse," a virtual, networked reality, as established in Stephenson's oeuvre.
It may simply be a reference, however, to an uncommon colloquialism.