entering currency in input box

[vk]

Hello,

I would like help with coming up with the simplest way to
enter a currency value in an input box in this manner:

1) if a person enters "5", the display value in the input
box should be:
"0.05"
2) next, if that person continues to enter the second
number of "9", the display value should now be:
"0.59"
3) if then, he enters "1", the display should be:
"5.91"

Essentially, the old numbers should shift to the left as
new numbers are entered and the two decimal place is
always kept.

Your help is greatly appreciated,

-vk