Round a double in Java

You have to replace

BigDecimal bigDecimal = new BigDecimal(d);

with

BigDecimal bigDecimal = BigDecimal.valueOf(d);

and you will get the expected results:

2.66
1.66

Explanation from Java API:

BigDecimal.valueOf(double val) – uses the double’s canonical string representation provided by the Double.toString() method. This is preferred way to convert a double (or float) into a BigDecimal.

new BigDecimal(double val) – uses the exact decimal representation of the double’s binary floating-point value and thus results of this constructor can be somewhat unpredictable.