With this online calculator you can calculate rounding to the nearest millionth.
Rounding to millionth is performed according to the rounding rules.
Example:
1.77777777 = 1.777778
1.33333333 = 1.333333
1.12222255 = 1.122223
Rounding to millionth is replacing a number with its approximate value, written with fewer significant digits after the decimal point.