I was working with statistics in Java 2 years ago and I still got the codes of a function that allows you to round a number to the number of decimals that you want. Now you need two, but maybe you would like to try with 3 to compare results, and this function gives you this freedom.

/**
* Round to certain number of decimals
* 
* @param d
* @param decimalPlace
* @return
*/
public static float round(float d, int decimalPlace) {
    BigDecimal bd = new BigDecimal(Float.toString(d));
    bd = bd.setScale(decimalPlace, BigDecimal.ROUND_HALF_UP);
    return bd.floatValue();
}

You need to decide if you want to round up or down. In my sample code I am rounding up.

Hope it helps.

EDIT

If you want to preserve the number of decimals when they are zero (I guess it is just for displaying to the user) you just have to change the function type from float to BigDecimal, like this:

public static BigDecimal round(float d, int decimalPlace) {
    BigDecimal bd = new BigDecimal(Float.toString(d));
    bd = bd.setScale(decimalPlace, BigDecimal.ROUND_HALF_UP);       
    return bd;
}

And then call the function this way:

float x = 2.3f;
BigDecimal result;
result=round(x,2);
System.out.println(result);

This will print:

2.30

Well this one works...

double roundOff = Math.round(a * 100.0) / 100.0;

Output is

123.14

Or as @Rufein said

 double roundOff = (double) Math.round(a * 100) / 100;

this will do it for you as well.

Keep in mind that String.format() and DecimalFormat produce string using default Locale. So they may write formatted number with dot or comma as a separator between integer and decimal parts. To make sure that rounded String is in the format you want use java.text.NumberFormat as so:

  Locale locale = Locale.ENGLISH;
  NumberFormat nf = NumberFormat.getNumberInstance(locale);
  // for trailing zeros:
  nf.setMinimumFractionDigits(2);
  // round to 2 digits:
  nf.setMaximumFractionDigits(2);

  System.out.println(nf.format(.99));
  System.out.println(nf.format(123.567));
  System.out.println(nf.format(123.0));

Will print in English locale (no matter what your locale is): 0.99 123.57 123.00

The example is taken from Farenda - how to convert double to String correctly.