Maybe GP was thinking of the optional rounding modes? With plain old add(), you get a BigDecimal 0.05 with scale 2 in both cases and the two examples are equal according to the equals() method.

    var a = new BigDecimal("0.0");
    var b = new BigDecimal("0.05");
    var result1 = a.add(b);

    var c = new BigDecimal("0.00");
    var result2 = c.add(b);
    System.out.println(result1); // 0.05
    System.out.println(result2); // 0.05
    System.out.println(result1.equals(result2)); // true
    System.out.println(result1.scale()); // 2
    System.out.println(result2.scale()); // 2