Dim myArray As Variant
myArray = Range("A4:A10").Value
Array indices start at 0, so LBound(myArrayabove) = 0 and UBound(myArrayabove) = 6
Using For i = Lbound(array) to Ubound(Array) means that doesn't matter.
I bet he also didn't tell you that the only Variables that don't need meaningful names are i, j, and k, because since before the birth of UNIVAC, those have been used as counters and indices.
For extra points, place your function in a Standard Module and declare it like this
Public Function TotalTaxes(Income As Double) As Double
That makes TotalTaxes a User Defined Function to Excel and it will be available with Excel's Insert Function routine at the Formula Bar.
Then in Cell E5 on your attachment, put this formula
Then you can place a list of incomes in D5 and down, and copy E5 down next to the list and see the taxes for each income.