How to achive the advance Pricing to apply the discount for the requirement like if a customer buy

Could you please  help me how to enable the modifiers for the below requirement.

Requirement
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"Actually we are looking for the requirement , let us say we have 5 item codes a, b, c,d and e. will eligible for 50 % discount and,
the same the first item A and second Item B line total is greater than 2000000 Rs then A will get additional 5 % and B will get 10 % discount.
For this we have created Modifier for 50 % discount and please let me know to approach for 2 discount based on the line totals."In the formulae its getting the discount based on the list price.