round to 0 or 5 at the 3 decimal place

[Peng Yu]

printf("%.3d", ...) rounds a number to the 3 decimal place. When the
number is less than 1, I want it to be rounded to the 3 decimal place
but the allowed number at that decimal place is only 0 or 5. I could
write some code based on conditional test to do this job. But
considering this might not be a very rare use case, is there an easy
way to do it?

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Regards,
Peng