How to fix calculation when handling costs?

Hi guys,

I was calculating costs and I notice the amounts in column D are correct but its calculated in correctly in cell N2 when referenced? I broke the calculation down in columns L through O. My other question is, I have the column D amounts formatted as Accounting, why does it show the .00 and if I remove it it is then formatted as Custom but the above two amounts are fine?

Thank you in advance if you can assist.