What is the method of sale for LPG in amounts over 5 gallons?

The correct method of sale for LPG (liquefied petroleum gas) in amounts over 5 gallons is by weight or volume. This is because LPG is typically sold in bulk quantities and can be measured either by its weight (in pounds or kilograms) or by its volume (in gallons or liters), depending on the preference of the seller and buyer. When dealing with larger quantities, volume measurement is common, but weight is also a valid method, particularly for commercial sales where precision is important.

Considering the other options, selling by price per ounce is more suitable for small quantities, typically not practical for LPG in bulk since it's usually not sold in such small measurements. Unit count refers to counting items, which does not apply to a fluid product like LPG. Selling by cubic feet could apply to gas sales, but for LPG, it is not the standard method for amounts over 5 gallons, while the established practices focus on weight or volume.