i found that there is some kind on glitch in the online brokerage calculator
attaching an image
1st image - It shows that a delivery bought at 91.3 and squared off at 100.9 gross gains woud be 960 then net gain after charges(44.82) should be 915.18, it displays 855.18 DIFFERENCE OF 60rs
2nd image - it shows that a delivery bought at 95.7 and squared off ta 100.9 gross gains should be 520
the net gain after charges (45.3) should be 474.7, it displays 454.7 difference of 20 rs
Enter the same values yourself and check on your behalf, Happy to Help