Beer (mild, bitter, lager, cider, etc.) can be bought in "pints" or "halves" (half-pints) (even where metric has superseded imperial).
Sugar can be bought in half kg or 1 kg bags.
A travel, amusement or entertainment ticket can be bought at half-price (children or senior citizen concessions, for example).
Some cooked poultry can be bought in halves, for example, roast chicken.
In restaurants steak can be sold in halves (half-pound steak, etc.) as part of a meal.
Fabric, material or timber can be bought in halves (half a foot, half a metre, etc.) or multiples of halves.
Items can be sold by weight, rather than quantity of items, in halves (half a pound, half a kilogram, half an ounce, half a ton, etc.).