This field indicates whether a price is calculated from the registered Price Including VAT for items
within this sales type.
If you have two sales types such as in-house and takeaway set up with different VAT %,
items will have a higher price including VAT (customer price) where the VAT % is higher,
unless you mark the sales types as calculating price from VAT price. If the sales types have a check mark in this field,
the price including VAT will be the same (customer price) for takeaway and in-house,
while the net price will be different.