Numerical integration is an important operation for scientific computations. Although the different quadrature methods have been well studied from a mathematical point of view, the analysis of the actual error when performing the quadrature on a computer is often neglected. This step is however required for certified arithmetics. We study the Newton-Cotes quadrature scheme and give enough details on the algorithms and the error bounds to enable software developers to write a correctly-rounded Newton-Cotes quadrature.