Adding Currency To Variable Range Of Cells?

I'm trying to create a sum that gives the output with the currency format but also change column D from from D2 to the Total the currency format. (it changes based on how many customers). Here is the code

Code:

Windows("Test1.xls").Activate
Dim rng As Range
Set rng = Sheets("Sheet1").Range("D65536").End(xlUp).Offset(1, 0)
Range("D" & lastrow + 4).Select
lastrow = Cells(Rows.Count, 1).End(xlUp).Row
Cells(lastrow + 1, 4).Formula = "=sum(D2:D" & lastrow & ")"
rng.Select ("D" & lastrow)
Selection.NumberFormat = "$#,##0.00"

I know it has to do with the rng.select statement but I'm just not sure how to make it work for all of Column D from D2 to the Total/Sum.