Probably left over from this deal :
https://www.ozbargain.com.au/node/143102
On a table near the escalators are the Reserve Shirts on clearance, if you look for RBSW13002 which is a blue stripe style, you will get another 75% off at the register Was 20-30 left at lunch. Maybe also in other Myers.
How is it $5.21 each? 75% off $25 is $6.25. You bought 5 shirts for $31.25 which is $6.25 each. Still a good price though…