In Nicaragua it is currently not possible to offer foreign interns direct payment through internships. Therefore companies here in Managua and Leon, are prepared to pay for lodging and sustenance.
Although this does not include travel costs between your home and the workplace there are many different ways to circumvent expensive travel. On the one hand, public transport is very inexpensive in Nicaragua. Bus fares between cities usually cost no more than 3 dollars, whereas local buses will transport you for about 25 dollar cents or in local currency about four cordoba. Taxis as well usually cost no more than 3-4 dollars, and in Leon you are perfectly welcome to use a bike.
In your spare time welcome you to explore the country. As already mentioned travel is fairly cheap and vacationing spots such as the Lago de Apoyo a famous Nicaraguan volcano lake or San Juan del Sur, a popular vacationing spot for locals and tourists aren't very far away.