Is that a question or a statement. If you can be a bit more clear, I can probably help out. Most commands will not require documentation for any total expenses under 75$. Anything over requires documentation, usually in the form of a receipt. Taxis and in and around mileage are usually the exceptions. In the past, what I have done is just keep a written log of origin, destination, mileage, & amount and then scan that into your substantiating documents when you file your voucher.