It's a question that has troubled the most frugal among us.

What purpose do the loose pieces of silver shrapnel that decorate the bottom of bags, the floor of the car, and deep crevices of couches really serve? What, in today's terms, can you buy for 5 cents?

These days you cannot make a 5-cent coin for 5 cents. While the cost of producing a 5c piece varies with fluctuating metal costs, "it costs approximately 7 cents to product the 5 cent coin," Ross MacDiarmid, head of the Commonwealth's Canberra coin factory, said.

Yes, the price of producing the clunky silver echidnas now outweighs the value of the coins themselves.