With the weeks, 2 day, day, and subs days rate engine, you can:
 set how much to charge if the rental is a single day
 set how much to charge if the rental is two days
 set how much to charge for subsequent days after the first full week
Charging periods
Charges for this rate are calculated as a percentage of the weekly rate. For your reference, the leading rental period is listed here as 100%, i.e. the rate you entered against the product.
1 day and 2 day
Specify the percentage you’d like to charge for if the rental is 1 day or 2 days.
If the rental period is more than two days but less then the rental days per week the charge will be rounded to a whole week.
Subs days
In the “Subs days” field, specify the percentage you’d like to charge for each day after the first week.
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.
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.