If you want buy one thing as a souvenir from Nicaragua, it should be a hammock. The best ones are made in Masaya, you can buy it at the fabrica de hamacas, the mercado viejo or the mercado nuevo, and the prices are the most variety and best. There also have local arts and crafts, such as San Juan del Oriente pottery and Masatepe furniture.
If you want to buy liquor, the local brand of Rum is Flor de Caña is the first choice and you can buy it in the local stores. It is available in several varieties: Light, Extra Dry, Black Label, Gran Reserva (aged 7 years), Centenario (aged 12 years) and a new top-of-the line 18 year old aged rum. There is also a cheaper rum called Ron Plata.
Shopping centers is mainly in Managua and the largest and most modern being MetroCentro near the rotonda Ruben Dario. The other one is Plaza Santo Domingo. Shopping like the locals at the mercados or public markets. The largest is Mercado Oriental, another is Mercado Huembes.