CC/Paypal Fee Calculator

stripe.js

const FIXED_FEE = 30; //The number of cents you are charged per transaction
const PERCENTAGE_FEE = .029; //The percentage of the transaction your processor will take in addition to the fixed fee

/**
 * This function calculates how much you need to charge your customer to recoup the cost of transaction fees
 * 
 * @param targetPrice The target number of cents you want to earn
 * @return The number of cents that you want to actually charge the customer, including fractions of a cent
 */
const calculateFee = (targetPrice) => (targetPrice + FIXED_FEE) / (1 - PERCENTAGE_FEE;

/**
 * This function calculates how much you need to charge your customer to recoup the cost of transaction fees
 * 
 * Note that this will round to the nearest cent in your favor.
 * @param targetPrice The target number of cents you want to earn
 * @return The number of cents that you want to actually charge the customer, rounded up to the nearest whole cent.
 */
module.exports = (targetPrice) => Math.ceil(calculateFee(targetPrice))