I just put in 30 dollars worth of apple store cards and I only got 5 dollars worth

As ed2345 mentioned if the gift cards have been redeemed you could try to sign out and back in to see if the balance shows up

If you can't redeem your App Store & iTunes Gift Card, Apple Music Gift Card, or content code - Apple Support

Jaden,

When you redeem cards on a computer, the balance updates immediately. When you redeem on an iPhone, the balance may not display until you log out of the iTunes account and log back in.