Adding muliple sum formulas in one column

Hello,
I have a spreadsheet which I converted from a PDF report with thousands of orders each of which have either single line items or multiple line items. The total for each line item is in column D and I would like to get a sum for each order and need to know what formula or macro I could enter rather than going to each cell and clicking autosum for the order range above.

For example range D3:D5 has dollar amounts for one order and D6 has #N/A, D7:D12 has dolalrs amounts for another order and D13 has #N/A, D14 has a dollar amount and D15 has #N/A. The list goes on and on.