I have a spreadsheet like

Name Price
name1 100
20
name2 200
name3 100
100
10

Can I write a formula that will give me a subtotal in column C
such as

Name Price Total
name1 100
20 120
name2 200 200
name3 100
100
10 210

Something like this might help.

Put the following in C2 and copy down
=IF(A2&B2="","",
IF(OR(A3<"",A3&B3=""),
SUM(B$1:B2)-SUM(C$1:C1),
""))