If - Then - Else Statement Problem: Next without For

Hello,

I am posting the following code to populate column 'D' with either "SGA" or "COGS" based on criteria in column C. If the data does not meet the criteria, I would like column D to display "N/A." My code is below:

Sub COGSorSGA()

Dim i As Long
Application.ScreenUpdating = False
    
    For i = 2 To Range("a" & Rows.Count).End(xlUp).Row
        If Range("C" & i) = 5 Then
            Range("D" & i) = "SGA"
        If Range("C" & i) = 30 Then
            Range("D" & i) = "SGA"
        If Range("c" & i) = 55 Then
            Range("D" & i) = "COGS"
        If Range("c" & i) = 80 Then
            Range("D" & i) = "COGS"
        If Range("c" & i) = 99 Then
            Range("D" & i) = "COGS"
        Else
            Range("D" & i) = "N/A"
    Next i

Application.ScreenUpdating = True

End Sub

Thank You!

Sam