Converted Value Rounding Off and Rounding Up/down

If there is no tolerance in the SI unit value, after conversion, rounding off is to within the number of significant digits.
If there is tolerance in the SI unit value and the figure after conversion indicates the upper limit, the number of digits is rounded down to within the number of significant figures. If it indicates the lower limit, they are rounded up to within the number of significant figures.
Even if the SI unit value is the same, the converted value may differ based on whether that value is the upper or lower limit.