Use this formula:
=MAX(1,ROUNDUP(10*PERCENTRANK($C:$C,$C2,4),0))
To divide into whichever many groups you need, change the value 10; it now creates decile groupings. Change $C2 to the cell in the first row with the target value and autofill down, then change $C:$C to the column with the target range of values.
Your result will be a division of the population into groups, with 1 being the lowest value and everything higher representing a higher value.