Right now its full pennies. If I think an event is possible but has a less than 1% chance of happening, give the option of buying shares for .001. Bigger profit potential.
iPredict had fractions of cents and it was very annoying because as soon as you put in a bid at $0.75, somebody else would put one in for $0.7501, then you'd raise yours to $0.7502 etc. etc. Tenths and hundredth of cents are more bothersome when placing bids than helpful.