If an option is to do the INSERT in the same stored procedure, the following code should work:
CREATE PROCEDURE `5star`()
BEGIN
DECLARE Rating5Total INT DEFAULT 5;
DECLARE Rating5Win INT DEFAULT 5;
DECLARE 5StarPerformance DECIMAL(18, 3);
SET Rating5Total := (SELECT COUNT(Ratings) FROM vHighPerformance WHERE Ratings = 7);
SET Rating5Win := (SELECT COUNT(Results) FROM vHighPerformance WHERE Ratings = 7 AND Results = 1);
SET 5StarPerformance := Rating5Win*100.0/Rating5Total;
/* INSERT INTO percentages (percentage) VALUES (5StarPerformance); */
INSERT INTO percentages (id, percentage) VALUES (1, 5StarPerformance)
ON DUPLICATE KEY UPDATE percentage = 5StarPerformance;
SELECT 5StarPerformance;
END$$
An example can be seen in SQL Fiddle.
UPDATE
If you need one single record on table percentages
, you can make a UPSERT. See the updated code.