Hello,

well the first problem is that you distributed percentage all wrong. Your sum gives back 110 and not 100 :))) it took me quite a while to figure it out.

I can give you this formulas but they are not ideal.

in a case where you have in a column A your names B,A,C,D,E (starting with the row number 2) and in column C you percentage. Cell B1 is the amount saved.
so in the cell B2 you would put, +IF($B$1*C2=15;15;$B$1*C2) this reffers to name B. And then in cell B3 you would put this and then drag it down to other cells:
+IF($B$1*$C$2<$B$2;($B$1-$B$2)*(C3+(1-SUM($C$3:$C$6))*(C3/SUM($C$3:$C$6)));$B$1*C3)

i dont know if this helps you, is not ideal formula cuz it assumes that you are always looking to stop contributing to the item B.