I've taught her the simple steps :
Queue Up
Speak Up
Ask How Much
Give Money
Wait for change (if any)
Sounds simple but a daunting task for a kid. I sent her to buy some kuih for me at our yumcha place and walk away, looking on from afar. When it's her turn, she chickens out or speak soo softly that the cashier cannot hear and when she's asked to speak louder, she'll chicken out and run back to me.
A little step at a time.
I'm sure, soon, I'll be complaining of a little shopper who is very confident in spending money $$$$$