The two-dimensional tricritical Ising model with an order parameter perturbation is studied using two different lattice models. The mass spectrum is found to be the same as in the 2D Ising model with a magnetic field. Results for the scaling functions are in agreement with universality and for the lowest mass a relationship with the scaling function of the Ising model is observed. The numerical results do not support a recent proposal of Dotsenko on the dynamical generation of extra terms in the perturbative calculation of scaling functions.