Regulations Governing Foreign Exchange Business of Banking Enterprises Article 37

(Obligation to Disclose Exchange Rates)The exchange rates used for foreign exchange transactions between a banking enterprise and a customer may be solely determined by the banking enterprise.The NTD exchange rate for a single foreign exchange transaction with a customer for an amount of less than US$10,000 shall be posted at the banking enterprises' business premises before 9:30 AM on each business day.
中文原文 銀行業辦理外匯業務管理辦法第37條
銀行業與顧客之外匯交易買賣匯率,由各銀行業自行訂定。
每筆交易金額在一萬美元以下涉及新臺幣之匯率,應於每營業日上午九時三十分以前,在營業場所揭示。

English translation for reference only; the Chinese text prevails. Not legal advice.