Target will stop selling cereals containing synthetic colors by the end of May. The Minneapolis-based discounter said Friday it had been phasing out synthetic colors in cereals for several years. Right now, 85% of its cereal sales already come from products made without synthetic dyes. Target said it has worked with national brands and its private labels to reformulate products. Target said ome cereals — including Trix and Lucky Charms, which are made by General Mills — will have updated formulations. Target said it will no longer carry brands that don’t reformulate, but it didn’t name the brands.