how long to cook a top round roast
3. Place top round roast, fat side up, on rack in shallow roasting pan. Do not add water or cover roast. 4. Cook in in the oven for about 2 1/2 hours or until the internal temperature reaches 140Â°F for medium-rare or 155Â°F for medium.5. Remove top round roast from oven and tent loosely with aluminum foil.6.Let stand 15 minutes prior to carving into slices.. Cook in in the oven for about 2 1/2 hours or until the internal temperature reaches 140Â°F for medium-rare or 155Â°F for medium. 5. Remove top round roast from oven and tent loosely with aluminum foil. 6. Let stand 15 minutes prior to carving into slices.