Brokerage for pyramiding

Hello Guys I have one doubt if anyone please help me with my query I will be thankful to you

Suppose I decided to buy nifty future for 4 lots but instead of purchasing at one go I decided to buy in pyramiding mode 1 lot at a time, But I sell these in 1 go

how much brokerage I will be charged it will be similar to the Zerodha calculator or it will be different please enlighten me

Buy 1 lot at a time but sold all 4 lots in 1 go

For buying, it will be Rs 20*4=Rs 80
While selling only Rs 20

Theoretically selling should be 20 , but practically it may note be if it gets executed as separate orders