I don't think there's such a rule. You can round a number as many times as needed. And it depends on how many decimal places you need to round to. So, if the task says to round the number to two decimal places, the result will be 0.45. But if you need to round to a whole number, then yes, it will be 1.
Example: 0.45 is rounded to 0
Example in stages (incorrect):
1) 0.45 is rounded to 0.5
2)
