Conditional formatting color fill based on nested if statement

I need to use a nested if statement to color a cell based on the values of different nonadjacent cells within a row.

So
If the Best price = Aldi then color the cell yellow
If the best price is Lidl then colour the cell orange
If the best price is Tesco then color the cell blue

I think I need to use the column that works out the price per 100g/litre etc instead of the actual store price column to do this (in reality the pack sizes may be different so I need these columns to work out the base figure)
Thanks