Suppose every customer has a variable customer worth and you want to assign a percentile bucket for each customer here is the calculation for that.
IF [Customer Worth]<={FIXED :PERCENTILE([Customer Worth],.1)} THEN "<10th" ELSEIF
[Customer Worth]<={FIXED :PERCENTILE([Customer Worth],.2)} THEN ">10-20th" ELSEIF
[Customer Worth]<={FIXED :PERCENTILE([Customer Worth],.3)} THEN ">20-30th" ELSEIF
[Customer Worth]<={FIXED :PERCENTILE([Customer Worth],.4)} THEN ">30-40th" ELSEIF
[Customer Worth]<={FIXED :PERCENTILE([Customer Worth],.5)} THEN ">40-50th" ELSEIF
[Customer Worth]<={FIXED :PERCENTILE([Customer Worth],.6)} THEN ">50-60th" ELSEIF
[Customer Worth]<={FIXED :PERCENTILE([Customer Worth],.7)} THEN ">60-70th" ELSEIF
[Customer Worth]<={FIXED :PERCENTILE([Customer Worth],.8)} THEN ">70-80th" ELSEIF
[Customer Worth]<={FIXED :PERCENTILE([Customer Worth],.9)} THEN ">80-90th" ELSEIF
[Customer Worth]<={FIXED :PERCENTILE([Customer Worth],1)} THEN ">90th" END