Dynamic tax calculator

[Roofasa]

ok, so I'm going to work through this step by step.

1. It's a sub and a function - I have a sub that calls the tax function. Don't ask me why this is necessary, the book just wants it
2. I have income as the input coming in from the sub - input box to request income
3. added a message box at the end of the function to display the results - once I have a result :P
4. Ok this is where it gets harder. Bear with me <3
I tried to fill the arrays. I am on the right track or am I just leading myself down the garden path?

Dim arrBreakPoint() As Integer
Dim arrTaxPct() As Double
Dim i As Integer
Dim totalTax As Double
Dim size As Long
With Range("a3")        
    size = WorksheetFunction.CountA(Range(.Offset(1, 0)), Range(.Offset(.End(xlDown), 0)))
End With
ReDim arrBreakPoint(size)
ReDim arrTaxPct(size)
With Range("a3")
    For i = 1 To size
        arrBreakPoint(i) = Range(.Offset(i, 0)).Value
        arrTaxPct(i) = Range(.Offset(i, 1)).Value
    Next
End With

Oh, an HW: looked up integer and double - looks like the difference is precision and the decimal place. Integer being whole numbers. So I changed my totalTax to double and the taxPct to double?

P.s I appreciate you basically teaching me arrays, I really do.