pow() supports fractional exponents of negative numbers like in Py3:

>>> from future.builtins import pow
>>> pow(-1, 0.5)
(6.123233995736766e-17+1j)

round() uses Banker's Rounding as in Py3 to the nearest even last digit:

>>> from future.builtins import round
>>> assert round(0.1250, 2) == 0.12