Summing cells of a unique color
 

Tried to use Help for this and got nowhere.

Office 365 Excel:

I have a column of cells that I have colored a background cell
color (blue) when they meet a simple criteria. I color them when
I enter the dollar amounts in the workbook.

I want to sum these colored values with the blue background and
only these values. (FWIW, about half the values in the column
have the colored background. The other cells are uncolored.)

How do I accomplish this? What conditions do I apply?

Thanks in advance for your help.