another way to average is to use a running average; give it a try
float tempValue = 0.0;
void tempS(int sensor)
{
float tempValue = analogRead(sensor) * 0.48828125 - 50; // shrunk the formula to the max ((AR * 5.0 /1024.0) -0.5) / 0.01
temp = 0.85 * temp + 0.15* tempValue; // new value counts for 15% <<<< this is the running average thingie, you can change the %% as long as the both add up to 1.0
lcd.setCursor(0, sensor -1); // optimized triple if
lcd.print("Temp");
lcd.print(sensor, DEC);
lcd.print(": ");
lcd.print(temp, 2); // # means decimal places
lcd.print((char)223); // degree
lcd.print("C");
}