place order and jump the que

How is it that when you place an order on the buy or sell side it jumps immediately 1/3 to 1/2 way up the que? There is a buy order for 450,000 @0.38 currently. It jumped immediately to about 1/3 of the way up the list below 2x 165,941 orders and the 2 x 165,941 orders are slowly slipping themselves down the list. How is this done? ASX would not allow me to speak to their trading watch desk and my broker Etrade could not give me an answer. Etrade are looking at it though, as I demonstrated by placing an order and they saw that it jumped the que.