addition calculation not giving correct answer

[lnjr]

I have a workbook with calculations for a sale less the assorted fees and at the end giving the final amount from a sale.

I have noticed that some of the rows are not giving the correct amount in them.
In other words the addition of some columns in that row are not adding up correctly. It is only off by 1 cent (either over or under), but I can't figure out why.

I have the feeling that I am going to want to kick myself when someone explains this to me (I just know that I know the answer but for the life of me I can't right now).

I have attached a spreadsheet to show you what I mean.

Thanks!