* Manufacturing falls 5.5 pct in June from May * Index rises smaller-than-forecast 1.1 pct year-over-year * Key rate seen held at 5.0 pct in August * Domestic demand remains firm By Moises Avila and Antonio De la Jara SANTIAGO, July 30 (Reuters) - Manufacturing production fell sharply in June from the previous month in Chile's export-dependent economy but domestic demand remained firm, reinforcing expectations the central bank will keep interest rates steady in the near-term