Heat oven to 500 degrees.
Have roasting pan with rack ready.
Cut tiny slits all over meat with the point of a sharp paring knife and slip the slivers of garlic into them.
Combine the oil, salt, chili powder and marjoram and rub all over meat (not on ends) using hands.
Set roast on rack in roasting pan, spread top with about 1/4 of the tomato sauce, and put in oven.
Turn heat to 325 degrees immediately and cook 25 to 30 minutes a pound for medium rare (if using a meat thermometer 140 degrees for rare, 160 degrees for medium and 170 degrees for well done), about 2 hours and 15 minutes.
Baste meat every 30 minutes during roasting and spread with some of the tomato sauce each time you baste.
Cool and chill.
Carry to picnic in cooler.
Slice thin to serve.