MONEY in middle earth?

[Pitchwife]

HoME XII, The Appendix on Languages:

farthing has been used for the four divisions of the Shire, because the Hobbit word tharni was an old word for 'quarter' seldom used in ordinary language, where the word for 'quarter' was tharantîn 'fourth part'. In Gondor tharni was used for a silver coin, the fourth part of the castar.

Unfortunately, we don't know what was the equivalent of a castar in Shire currency, nor what the fourth part of a castar amounted to in smaller coins. If I had to guess, however, I'd bet the hobbits didn't use anything as modern as a decimal system, rather something like the old English pound/shilling/pence thing.
Likewise, we don't know how much a loaf of bread cost in Middle-Earth (not as far as I can remember, anyway), but we know the price of a pony, which was about four silver pennies (FoTR, A Knife in the Dark):

Bill Ferny's price was twelve silver pennies; and that was indeed at least three times the pony's value in those parts.

Hope that helps.

(EDIT: cross-posted with Rumil.)