I don't know how to do exactly what you are asking, but this might help.
Goto Tools-Options-Calculation and select "Precision as Displayed". Then
format the fields to a number with two decimal places. Then when someone
enters 43.703 it will convert the number to 43.70 automatically (not just the
output). However if someone enters 43.709 it will convert the number to
43.71 automatically. This actually rounds the cell value to the nearest
100th place. It's not just changing the output, and you will permanently
lose any precision beyond the 100th place.

"Tim" wrote:

I have a multi-user spreadsheet to enter dollar values. How can I limit a
user from entering, for example, 43.703 when the correct entry is 43.70?

I can do this by changing the number format but do not want to do that.