IB has two models for charging commissions: fixed and tiered.

According to this page on IB's web site, the tiered commission model works a lot cheaper for high volumes (per month):



Currently I'm using this line in my code for paper trading:

SetBrokerageModel(BrokerageName.InteractiveBrokersBrokerage, AccountType.Cash);


This actually sets the default fixed commission model which is $0.005 per share with a minimum of $1 per order. Now my question is, if we change the IB account to use a tiered model:

1- is there a way in LEAN to simulate charges based on IB's tiered model for paper trading? (I know how to create custom SecurityTransactionModel if that's the answer)

2- when live trading, does LEAN get the charges from IB? or it calculates charges based on the default fixed IB model?