Enumerating Smartly in Excel

Hi I have an excel question - I need to have the function be smart enough to do two things:

1.  Determine the first integer of a value (ex x.xx) using Report Category column (SEE BELOW) based on 1-5 Values  

2.  Find the largest value in the column with the numbers in it and add .01 to it.  This is the hard part as the first integer needs to be taken into consideration first and then look at the trailing 2 integers after the <.> to get the value to start with then add the .01 to it.   

Below is an example of what I have so far showing what I need - NOTE IT WILL NOT BE IN PERFECT ORDER BY THE REPORT ID - IS FOR THIS EXAMPLE ONLY:

I used this function to get the first integer   =IF($D4="External Client Regulatory","1.",IF($D4="External Operational Request","2.",IF($D4="Evolent Standard Operational","3.",IF($D4="Evolent Vendor Operational","4.",IF($D4="Evolent Internal Operational","5.",0)))))

But after that I can't figure out what to do to get the correct trailing numbers.    It does not need to be dynamic as we often times add and delete rows from the output so the numbers should stay the same once they are assigned.  

Report ID  Report Name                                                    Report Category