&gt; &quot;When you present prices to your customers, you must state the total price of the good or service as a single figure, which is the minimum total cost that is able to be calculated.&quot;<p>Interesting. Suppose you go into a fast food place and say &quot;I&#x27;ll have a burger, medium onion rings, and a small soft drink&quot;. Assume onion rings come in medium and large, soft drinks come in small, medium, and large, and fries come in small, medium, and large. Assume onion rings and fries of the same size cost the same, and one can be substituted for the other in a combo with no price change.<p>The clerk could ring this up as those three separate items as ordered, giving price P1.<p>A second option is to ring it up as a medium combo (Burger, medium fries, medium drink), substitute onion rings for fries, and downgrade the drink to small, giving price P2 which is less than P1.<p>A third option is to ring it up as a small combo (Burger, small fries, small drink), upgrade to medium fries, and then substitute onion rings for fries, giving price P3 which is less than p2.<p>Is the seller in violation of the law if the clerk does not figure out and use option three?<p>How about an order for multiple people but all on the same ticket? For example here in the US Arby&#x27;s has gyros for a limited time. They are something like a little over $4 each, but they have a 2 for $6 deal. Suppose a family of 5 comes in. The husband orders, then each kid orders, then the wife orders and pays. Suppose 3 of the 5 people ordered a single gyro each. If this were in Australia, would the clerk be required to notice that he can put two of those gyros together and ring them up as 2 for $6?