jmc

We simplify the inequality by subtracting $5$ from all 3 values to yield $$-8\le x\le 3.$$ The integers in this range are the possible solutions, and to find their sum, notice that we can group certain numbers with their opposite to sum to 0, namely $$(-3+3)+(-2+2)+(-1+1)+0=0.$$ Since these numbers contribute a sum of $0$, we now only need to find the sum of the integers from $-8$ to $-4$. Their sum is $-8-7-6-5-4=-30$, and hence our answer is $\boxed{-30}$.