Unbiased rounding can be carried out in the following way.

• If the digit to be rounded is followed by a digit less than 5, it is left unchanged;

• If the digit to be rounded is followed by a digit greater than 5, or a 5 followed by non zero digits, it is increased by 1;

• If the digit to be rounded is followed by a 5 standing alone or followed by a zero, the decision to leave unchanged or to increase by 1 is decided from random number tables.
  Some authors suggest that it is left unchanged if it even, but increased by 1 if it is odd. However, this assumes that there is no odd-even bias in the data which may not be the case.