Payment processors have historically relied on static billing models and broad merchant segmentation, creating structural inefficiencies in an increasingly dynamic digital commerce environment. Transaction-level costs, risks, and strategic value vary materially with context—channel, geography, funding source, payout timing, merchant behavior, and dispute outcomes—yet legacy pricing systems treat these dimensions as uniform. This article presents a modern pricing architecture that transforms the pricing engine into a real-time economic decision layer, combining transaction-level cost and loss forecasting, competitive and elasticity-aware optimization, continuous post-settlement learning, and an integrated incentive layer for promotions and merchant-funded campaigns. The platform employs machine learning for predictive components and large language models for unstructured signal extraction, enabling a pricing system that remains auditable, adaptive, and aligned with long-term network health. Implementation through governed architectural layers, deterministic fee construction with explainable components, event-driven lifecycle data contracts, and closed-loop learning mechanisms demonstrate how economic precision and transparency can coexist. Evaluation methods combining controlled experimentation, causality validation, and lifecycle measurement ensure that pricing decisions improve both processor profitability and merchant experience without sacrificing either regulatory compliance or competitive positioning.