Coding multiple RFID to display information

Projects General Guidance
1

Hi guys, I'm currently writing a code for grocery system using RFID and Arduino.

I'm stuck at the following code whereby I'm trying to display the information when a certain RFID is being tagged. Multiple tags with different information will be used.

char tagA[] = {0x80, 0xD6, 0xD0, 0xA6};

 if ( findID(readCard)== tagA[])  {        // If not, see if the card is in the EEPROM
        Serial.println("ITEM A");
        lcd.clear();
        lcd.setCursor(0, 0);
        lcd.print("PRICE = $1.50");
        lcd.setCursor(0, 1);
        lcd.print("EXPIRY = 22/08");
        addPriceA();
        lcd.print(sum);
        digitalWrite(8, HIGH);
        delay(1500);
        digitalWrite(8, LOW);
        lcd.clear();
      }
      else {        // If not, show that the ID was not valid
        Serial.println("NOT IN SYSTEM");
        Serial.println("SCAN AGAIN");
        lcd.clear();

Question:
How do make sure different RFID, when tagged, will display their respective information?