perl group by and sort from a csv input file

gowthamvels has asked for the wisdom of the Perl Monks concerning the following question:

I need to write a PERL script to group and sort the CSV file with below sample data
The sample data from a input file looks like below.

SAMPLE INPUT INPUTFILE.csv
3211111,100,3.2 
3211112,101,3.2 
3211111,100,1.2 
3211112,100,2.2 
3211113,100,5.2 
3211112,100,0.3
[download]

I need to group first two columns and sum up the third column to obtain below output file -

outputfile.csv 
3211111,100,4.4 
3211112,100,2.5
3211112,101,3.2
3211113,100,5.2
[download]

Please help me out.

2017-07-27 Athanasius added code tags