Sum of Order Total Based on Unique Order ID

Hello,

I'm trying to get the sum of a Column B based on the unique values in Column A. For example, column B has order totals and column A has the order IDs. Below is example of data from my spreadsheet. A couple things to note: 1) there's not always a pre-defined number of rows. 2) Order IDs are not always known so the function cannot specify the unique order IDs.

I'm sure there's a way to do this, but cannot seem to figure it out. I've tried pivot tables but it's just giving the total sum of Order Total, instead of the Order Total based on unique Order IDs. This would be easy to do in a database, but I need an Excel solution. Any help is appreciated!

[QUOTE]
Order Id Order Total
3203768 9.95
3203769 98.95
3203770 125
3203771 63.12
3203771 63.12
3203772 164.95
3203773 101.7
3203774 67.04
3203774 67.04
3203774 67.04
3203775 29.95
3203776 119.99
3203777 178.95
3203778 99.95
3203779 79.16
3203781 248.95
3203782 164.95
3203783 498.95
3203784 79.95
3203785 94.32
3203785 94.32