Using last unique enteries, need to sum up the last cost

[frankthetank81]

[TABLE="width: 500"]
<tbody>[TR]
[TD]Issue
[/TD]
[TD]Cost
[/TD]
[/TR]
[TR]
[TD]1
[/TD]
[TD]5
[/TD]
[/TR]
[TR]
[TD]1
[/TD]
[TD]10
[/TD]
[/TR]
[TR]
[TD]1
[/TD]
[TD]8
[/TD]
[/TR]
[TR]
[TD]2
[/TD]
[TD]12
[/TD]
[/TR]
[TR]
[TD]2
[/TD]
[TD]15
[/TD]
[/TR]
[TR]
[TD]2
[/TD]
[TD]20
[/TD]
[/TR]
[TR]
[TD]2
[/TD]
[TD]25
[/TD]
[/TR]
[TR]
[TD]3
[/TD]
[TD]50
[/TD]
[/TR]
[TR]
[TD]3
[/TD]
[TD]30
[/TD]
[/TR]
</tbody>[/TABLE]

I am trying come up with a way to sum the last cost (column b) with respect to the last issue so that the total cost can be reported out.

 

[AhoyNC]

Something like this?

Excel Workbook
	A	B	C	D
1	Issue	Cost
2	1	5
3	1	10		80
4	1	8
5	2	12
6	2	15
7	2	20
8	2	25
9	3	50
10	3	30
Sheet

 

[frankthetank81]

But 80 is not the answer for that, 63 would be?

 

[frankthetank81]

Sorry I should clarify better, I need the last cost for the 1s, 2s, and 3s summed up

 

[AhoyNC]

This seems to work based on your sample.
It's an array formula and must be entered with CTRL-SHIFT-ENTER.

Excel Workbook
	A	B	C	D
1	Issue	Cost
2	1	5		63
3	1	10
4	1	8
5	2	12
6	2	15
7	2	20
8	2	25
9	3	50
10	3	30
Sheet

 

[frankthetank81]

Thank you so much, very appreciated