We study in the inviscid limit the global energy dissipation of Leray solutions of incompressible Navier-Stokes on the torus T d , assuming that the solutions have norms for Besov space B σ,∞ 3 (T d ), σ ∈ (0, 1], that are bounded in the L 3 -sense in time, uniformly in viscosity. We establish an upper bound on energy dissipation of the form O(ν (3σ−1)/(σ+1) ), vanishing as ν → 0 if σ > 1/3. A consequence is that Onsagertype "quasi-singularities" are required in the Leray solutions, even if the total energy dissipation vanishes in the limit ν → 0, as long as it does so sufficiently slowly. We also give two sufficient conditions which guarantee the existence of limiting weak Euler solutions u which satisfy a local energy balance with possible anomalous dissipation due to inertial-range energy cascade in the Leray solutions. For σ ∈ (1/3, 1) the anomalous dissipation vanishes and the weak Euler solutions may be spatially "rough" but conserve energy.