Summing up positive and negative values

[pandyav]

I have the following values in Column B:
Column B
$946
$(354)
$2,371
$421
$(217)
$221
$621
$(354)
$(354)
$(167)

I want to display the sum of previous positive values if the number changes from positive to negative and sum of negative values when values start changing from negative to positive.

I am trying to create a result that looks like below:
Column B Column C
$946 $946
$(354) $(354)
$2,371
$421 $2,792
$(217) $(217)
$221
$621 $842
$(354)
$(354)
$(167) $(875)

Is there a way to accomplish this by any formula. Appreciate any help in advance.

[Ron Coderre]

With your sample data beginning in cell B1

Here's one approach...
C1: =IFERROR(IF(SIGN(B1)<>SIGN(B2),SUM(INDEX(B:B,LOOKUP(2,INDEX(1/(SIGN(B$1:B1)<>SIGN(B1)),0),ROW(B$1:B1))+1):B1),""),B1)

Copy that formula down as far as you need.

Is that something you can work with?

[pandyav]

That works perfectly, thank you so much.