Green’s Dictionary of Slang

oddy n.

also oddie

[the ‘odd halfpenny’ in a sum of money or a price]

(Aus.) a halfpenny.

1955		N. Pulliam I Travelled a Lonely Land (1957) 236/2: oddie – a halfpenny.
1984		Partridge DSUE (8th edn) 817/2: earlier C20.