datagrid view to iTextsharp report

Question

C#, visual studio 2015, Desktop Application, MS Access Database. I have a datagrid view like this: 

  

Item	Price
A	3
B	4
A	5
B	6
A	3
C	2
C	1

 

I want the result like this:

Sl. No.	Item	Total Price
1	A	11
2	B	10
3	C	3

 

How is it possible? please give me a link or example or sample code that I can understand.