The English groat was also in the grosz family.
I think that announcing the demise of subunits whose main unit is still used is somewhat premature (this applies to all the öre/øre/aurar) because there is at least a possibility that at some point a revaluation will take place. If that happens, it is highly likely that the old name for the subunit will be brought back, as happened in Iceland in 1981, Russia in the 1990s and France in 1960. In these cases before the reform there were no aurar/kopeiki/centimes in general use but they returned when needed. AIUI Iceland is actively considering both joining the EU and using the euro (whether as a genuine member of the eurozone or in the sense that Montenegro and Macedonia use the euro). But if it decides against the latter, I could well see that they might revalue the currency, which would see the return of the eyrir.
The penny has been all but wiped out: now AFAIK only sterling and the island currencies that exist at a par with sterling have pennies, either actually or theoretically. Australia, NZ, South Africa and various other countries lost their pennies on decimalisation in the 1960s and the Irish lost theirs when they adopted the euro. I'm not sure I accept the Bosnian fenig as a variant of the penny. It is consciously modelled on the pre-euro German Pfennig, yes, but the words Pfennig and penny, and the currencies they describe, have been separate for over 1,000 years. If they are to be combined so we must also combine all the Latin-based cent-words and all the Slavic ones, so Bulgarian and (old) Slovenian stotinki/stotinov are basically the same as centimes, cents etc.
Is the Czech Republic the only country still to use a variant of heller?
