How Point of Rental can handle your Item (such as fuel or tax to be sold) to the 100ths and 1000ths. Below is the setup you can do to accomplish this.
Create the following items:
1. Name - "Fuel per 100ths or 1000ths"
2. Quantity should be what you have on hand in inventory.
3. Type: Sales Fractional qty.
4. Enter Sales price to be 100x or 1000x $Actual Price per gallon -- Set that number in Sell price. Ex. 100 x 1.9984= 1998.40 Sell Price
5. Mark item as bulk in the options tab

Create a second item file
6. Name” Per Gallon Fuel"
7. Enter Fictional quantity of this item.
8. Type: Sales Item
9. No Sell Price
10. Mark item as bulk in the options tab

Once you have Created these items you will need to add the first item as a packaged item to the second. You can do this by selecting the record again and going to tools – package items. As shown below:
Add the correct value .001 in the quantity and select the Price Per Gallon Item. As Shown below

When you add this item to the contract it will now charge the rate you are wanting to charge.
