Hi buddy, thanks for your question. .  For calculating aggregate marks you need to add all the %ges of marks you received from 1st to 5th semester then divide it by 5 and you will get the required aggregate percentage and if you wish to convert into cgpa.. Then multiply your aggregate percentage with 0.5 and add it to your aggregate percentage.  For eg if you got 80% then 80+0.5(80) =84 ie 8.4 cgpa

I hope you got it 

All the best