Excel formula to sort into bins.

 With VBA

Function MyBins(MyValue As Single) As String

Application.Volatile

        If SGPValue > 1 Then
               MyBins = "> 100%"
        
       
        ElseIf MyValue <= 1 And MyValue > 0.8 Then
           MyBins = "100%-80%"
        ElseIf MyValue <= 0.8 And MyValue > 0.65 Then
           MyBins = "80%-65%"
        ElseIf MyValue <= 0.65 And MyValue > 0.5 Then
           MyBins = "65%-50%"
        ElseIf MyValue <= 0.5 And MyValue > 0.2 Then
           MyBins = "50%-20%"
        ElseIf MyValue <= 0.2 And MyValue >= 0 Then
           MyBins = "20%-0%"
        ElseIf MyValue < 0 Then
           MyBins = "< 0"
        
       Else
           MyBins = "Please Verify"

           
    End If
 
    
End Function

Without?
Would you use IF for that purpose? And when there are several bins you will have plenty of nested IFs?
The answer is to use LOOKUP. cf.: http://www.mrexcel.com/forum/excel-questions/631008-excel-formula-sort-into-bins.html#post3130377 In this example you can also see how an array, a table, can be encoded in a formula.
I think it is very neat to use ListObject Table to keep the parameters in, then the formula would look like:
=LOOKUP(B3;Table1[a];Table1[b]) where [a] is a column with upper limits and [b] contains the corresponding names of the bins.

Table 1
a            b
-99999  < 1
1           1 to 1,9999
2           2 to 4,9999
5           5 to 9,9999
10         10 and avobe

To count bins to generate a histogram it is probably best to use countifs:
http://exceluser.com/formulas/countifs-frequency-distributions.htm