Backend Coin Transaction Fee Adjustment

I have a backend system that needs tweaking. Specifically, I would like to make adjustments to the coin transaction feature. Currently, all transactions, regardless of the coin amount, are incurring fees. I want to change this so that transactions over a certain amount of coins are exempt from remittance fees.

Key Requirements:
- Adjust the backend system to exempt transactions over a certain coin amount from remittance fees
- Implement the exemption based on a specific percentage reduction

Ideal Skills:
- Proficiency in C
- Strong understanding of backend development and database management
- Experience with transaction fee implementation and adjustment
- Familiarity with cryptocurrency transactions would be a plus

Your main deliverable will be a backend system that accurately exempts transactions over a specified coin amount from remittance fees.