Home Postcodes by state WA 6168 Postcode 6168 6168 is the postcode for 7 localities in WA: Cooloongup, East Rockingham, Garden Island, Hillman, Peron, Rockingham and 1 more. Localities with postcode 6168CooloongupWAEast RockinghamWAGarden IslandWAHillmanWAPeronWARockinghamWARockingham BeachWA Postcode 6168 State or territory Western Australia (WA) Localities 7 Council area Rockingham Council area based on Australian Bureau of Statistics data (ASGS Edition 3), CC BY 4.0. Postcode 6167 · Postcode 6169