a 0,05 FRF or as you would note down 0.05 FRF. (1/20 of a FRF)
If you do a query on France now you will see that 3,917 casino items from France have no denomination (query = x) what so ever on the chip/ jeton/ plaque.
Only 526 have any indication (query = F) like F, fr, Fcs, Francs, etc. all being the FRF. Even the centimes, cent., c 's are under this category.
So putting a c was to make clear that this was a 5 cent (centimes) and of course not a 5 "cent" or 500, this one would have been marked with Cinq Cents Francs.

It's a beauty and compared to the 1F in almost mint condition.

Still not certain of the origin and that is why we will put it in C.Paix in France, because there are multiple leads.

Some items take time to find the origin. But that you know.

Jo