How would you make and Excel formula for this? Thanks!

10. Because larger jobs have certain economies of scale in setup and cleanup, a discount is given based on these estimated values to jobs based on their total size. Just below the grand total, determine the total discounted price of the job based on the following: If the total cost of the painting job is less than $800, then there is no discount. If the total cost of the painting job is at least $800 but less than $2,000, then a 5% discount will be given (discount is calculated based on the grand total cost for all items and all rooms). If the total cost of the painting job is at least $2,000 but less than $5,000, then a 10% discount will be given. If the total cost of the painting job is $5,000 or more, then a 15% discount will be given