Dani Johnson, multimillionaire, cuts tubes open and then closes them with a bobby pin to get every last bit.
I have been doing this for years, except a tube wringer works even better! It gets every last bit. You can buy this in an art store for squeezing tubes of paint. Use it on toothpaste, conditioner, or anything that comes in a tube. Just when you think you are out, you will have a week or more left!