To achieve the best pricing, I’ve found that adding 27.5% to the retail price works effectively. This approach was originally mentioned in a wiki that has since been deleted or shut down.

So as an Example if we take Flour ($2,94)
To calculate ( 2.49 + 27.5\% \) of 2.49:

1. First, find 27.5% of 2.49:
2.49 times 0.275 = 0.68475

2. Then, add this value to 2.49:
2.49 + 0.68475 = 3.17475

So, ( 2.49 + 27.5% ) of 2.49 equals ( 3.17475 ).
This equals $3.17

It would be dumb to not give you an Table with all the Prices so here you go feel free to share it and use it as you like!