Ah Rodney
I think it is you who has it wrong.
From the ABS dated 27 July 2016
The CPI rose 1.0 per cent through the year to the June quarter 2016. This is the weakest annual rise since the June quarter 1999.
The rises and falls are not rises and falls from a set base number as you suggest, I.e. 5% +/- the rise and fall.
The CPI is a basket of good and services which they measure cost variations in order to determine a number which is just a number. It doesn't accurately reflect the cost of living changes as not everyone buys everything in the basket.
People hang their hat on CPI as the holy grail upon which cost of living payrise should be based,however in times of low inflation the make up of the basket of goods which goes into calculating the CPI can actually show a reduction in the cost of living. If you go with CPI you could well be selling yourself short.
It is swings and roundabouts of course and in times of high inflation CPI usually delivers a better payrise than the company is prepared to offer.