Answer
See explanation.
Work Step by Step
The Heisenberg Uncertainty principle for matter does state that the energy of a system has uncertainty. Strictly speaking, that does mean that the energy of a system is not constant down to the very last decimal place. However, for all intents and purposes, energy is still conserved, because $\Delta E$ is tiny enough to neglect, i.e., it is practically zero, for any measurement of reasonable length $\Delta t$, due to the small value of h.
