With the daily rate engine, you can set up a simple daily charge. This is generally the price x quantity x chargeable days.
For example, 2 x product at $10 for 5 days would be $100 since $10 x 2 x 5 = $100.
Options
Day type

Calendar day
The number of days to charge is based on whole days; the start & end times aren’t taken into consideration. 
24 hour clock
The number of days to charge is based on 24 hour periods; the start & end times are used to calculate rental charging.
For example, a rental that starts January 2nd at 11am and finishes on January 3rd at 9am would be considered two days rental when using “calendar day” since it falls over two whole days, and would be one day of rental because the end time is earlier than the start time.
Rental days per week
Use this option to determine whether weekend days are considered chargeable. If you do not charge for Saturday or Sunday set this to 5, otherwise leave at the default value of 7.
Minimum rental days
The minimum number of days to charge, for example if this was set to 2 and an opportunity started and finished on the same day, Current will charge for two days as a minimum.
Keep in mind that if you enable chargeable days on an opportunity, Current will ignore the minimum rental days.
Leeway minutes
This option is only used when the day type is set to 24 hour clock. It adds a grace period or tolerance to the end of a rental.
For example, if a rental that starts January 2nd at 11am and finishes on January 3rd at 11:30am then the total rental period is 1 day and 30 minutes. This is considered two days of rental charge. However, if you set 60 leeway minutes then the same period would be considered one day of rental charge as 30 minutes is less than the leeway minutes.