Name the total number of roll for st joseph's school when decile is less than 5
CREATE TABLE "central_hawke_s_bay_district" (
  "name" text,
  "years" text,
  "gender" text,
  "area" text,
  "authority" text,
  "decile" real,
  "roll" real
);
SELECT COUNT("roll") FROM "central_hawke_s_bay_district" WHERE "name"='st joseph''s school' AND "decile"<5;