i have the job guide 2004 book and under retail manager and under education and training it says:
you can work as a retail manager without formal qualifications. Skills are usually developed on the job or through in house courses following recruitement as a sales assistant, and then advancing to supervisory and management positions. Sompe people enter this occupation by buying and running their own store. You will probably get some informal training on the job. However, entry into this occupation would be improved with traineeship in retail management. Entry requirements may vary, but employers generally require year 10.
hope that helps