A retail installment sale is a transaction between you and a dealer to purchase a vehicle where, you agree to pay the dealer over time. Use a California business purchase agreement to record the sale of a business.Download your free template today. This purchase is subject to all California sales tax. Municipalities are exempt from federal excise and transportation taxes. Use a Business Bill of Sale to set out the terms for the sale of a business and transfer the ownership and all assets to the buyer. California law prohibits a dealership from giving a customer a purchase agreement before the vehicle is on their property.