rounding floats to a number of bits

[Skaperen]

the round() function works on rounding to a number of decimal digits. is there a way to round a float to a number of bits?

[luoheng]

>>> round(3.567, 2) # the second para is number of bits round
3.57
>>> round(3.56784, 4) 
3.5678
# care with round
>>> round(3.5)
4
>>> round(4.5)
4

[Skaperen]

my documentation (for version 3.7.4) says that the 2nd argument of round() is the number of decimal digits (e.g. a reciprocal of a power of 10.0). but, i want bits (e.g a reciprocal of a power of 2.0).