Tax rates vary by state, vehicle type and even rental period. For example, in Austin, TX, a trailer rental of less than 30 days is 10%, but for 30+ days, the tax drops to 6.25%.
Keep in mind that most states require you to have a tax license or permit to collect sales/rental tax. Please contact your local department of revenue to learn more. For the most accurate and up-to-date information, please consult with a tax professional.