A double with a value of 2.5 is the exact same double as one with a value of 2.50. The number of decimal places only comes into play in the String when you format the double. If your requirements really dictate a certain number of decimal places in the stored numerical value, you'll have to use BigDecimal. However, unless you're dealing with money or with numbers outside of double's range or precision, most likely you can just sling doubles around and only worry about the precision when it comes time to display.
Also, why are you mixing floats and doubles? There's almost never a reason to use float in
Java, except maybe in a small-memory or small-cpu context. And if you are using them, it doesn't make sense to mix them with double.