In response to porsche:

If you are rounding numbers in a scientific setting, there are different rules to follow.

Examples (each rounded to one decimal place)

1.59 becomes 1.6
1.99 becomes 2.0
1.25 becomes 1.2
1.35 becomes 1.4
1.04 becomes 1.0
1.666... becomes 1.7

If you notice that 1.25 becomes 1.2 and 1.35 becomes 1.4, that is because 5 rounds to the even number.
Also, if you are rounding to one decimal place, you must have that place in your rounded number. 1.99 rounded to one decimal place does not become 2; it becomes 2.0.