Section 5. Whoever on Sunday keeps open his shop, warehouse, factory or other place of business, or sells foodstuffs, goods, wares, merchandise or real estate, or does any manner of labor, business or work, except works of necessity and charity, shall be punished by a fine of not less than twenty dollars nor more than one hundred dollars for a first offense, and a fine of not less than fifty dollars nor more than two hundred dollars for each subsequent offense, and each unlawful act or sale shall constitute a separate offense.