The following code from the 4.2 API examples seems to work ok for me. I enter 23.454 and blur the field and I get 23.45. I enter 23.399 and I get 23.4 since the decimalPrecision defaults to 2. What are you seeing?
title: 'Personal Info',
minValue: 0, //prevents negative numbers
// Remove spinner buttons, and arrow key and mouse wheel listeners