hidden subtotal that controls color of values in a column when a certain total is reached

I asked this question in another way in another post but then thought of this but I dont know how to implement it. I have a column that is formatted to US dollars in which a monetary value is entered in weekly. When there is $5000 in that column I would like the $5000 to turn red and every value entered after that to let me know that $5000 has been reached. I was wondering if there was a way to do this with a running hidden subtotal with some conditional formatting after that. I dont know how to do either so please assist me and feel free to talk to me as if I am an idiot because when it comes to excel, I am.