For sales and use tax purposes, soft drinks, bottled water, alcoholic beverages, candy and confectionery are not "food." The sale of any of these items is, therefore, not entitled to any of the exemptions for sales of food, including the exemptions for sales of food by volunteer fire companies and veterans organizations. Neither water nor ice is food, although they may be treated as food when sold as components of food.
Maryland does not charge a tax on regular food bought in a grocery store. There are lots of exceptions depending on when you plan to eat the food etc.
Wikipedia has a good summary of sales tax laws in all states.