feat: Implement tiered fee discounts for merchants based on transacti…

[Abdulazeem-code]

…on volume.

Description

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Code refactoring
• Test improvements
• Other (please describe):

Related Issues

Fixes #

Changes Made

Testing

• I have added tests that prove my fix is effective or that my feature works
• All existing tests pass locally
• I have tested this manually

Checklist

• My code follows the project's style guidelines
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published

Screenshots (if applicable)

Additional Notes

closes #144

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[codebestia]

GM @Abdulazeem-code
Please Fix the Conflicts and the CI.
The Build is failing.