There are 2 kinds of brokerage rates out there, online rates which is 0.42% or a minimum of RM28(or less) which ever is more and 0.6% or minimum RM40 for trades with remisier/broker whichever is more.

On top of that, you need to pay 0.03% for clearing fees and also RM1 for every RM1000 as stamp duty.

1. I assume your friend uses online trading so the breakdown would be;

RM6.35 x 1000 shares = RM6350 purchase

RM6350 + RM28 brokerage fees = RM6378

RM6378 + 0.03% = RM6379.91

RM1 for every RM1000 means for RM6379.91 = RM7 stamping duty

So your final price would be RM6379.91 + RM7 = RM6386.91 (RM36.91 of brokerage fees and stamping duty)
2. If your friend decides to sell at RM6.60, the calculation will be;

RM6.60 x 1000 shares = RM6600 sales

RM6600 + RM28 brokerage fees = RM6628

RM6628 + 0.03% = RM6629.99 (rounded)

RM6629.99 + RM7 stamping duty = RM6636.99 - RM6600 = RM36.99 brokerage fees

Profit therefore is RM6600 - (RM6379.91 + RM36.99) = RM183.1