how to calculate the total power dissipation of below circuit
Take the sum of all the supply voltages multiplied by the respective currents that they supply. You can do this in LTSpice by using {formula} such as: -

AVG(V1*I(V1))

That gives you the average power provided by V1 and, in case there are negative supplies you might be able to use ABS(x) to make the average powers all positive.

You just plot it and look at the graph.

That's how I remember doing it when I once used LTSpice so, if I've got something wrong in the ABS or AVG bits I apologize right now.