Decimal rounding is non-trivial in binary arithmetic. ISO standard round to even is more rare than typically assumed as most decimal fractions are not exactly representable in binary. Our 'roundX()' versions explore differences between current and potential future versions of round() in R. Further, provides (some partly related) C99 math lib functions not in base R.
Versions of round(x, digits) for R. This is less trivial than you may think: Numbers (and arithmetic) is in binary, rounding (apart from digits=0) is to decimals.