Family Dollar

I made a purchase at the store when I checked out I paid with $100.00 bill my total was $20.22 the casher handed me my change didn't count it back to me she was busy talking to her coworker I left the store I went picked up my kids at school I did not atop anywhere else but when I finally got home and went through my purse realized that she had missed counted and only gave me 2 twenties 1 ten 1 five 4 ones 3 quarters and 3 pennies that 100.00 was the only money I had to my name so I knew she had made a mistake I looked back on my receipt and I called the store she said it had been 2 hours and they has already changed shifts