She may have taken a photo of the register without paying 6 times. But on the day she is approached to address this, if she is apprehended before she has left the store she could use since there is no theft until she leaves. She can be warned or cautioned. You can ask for her receipt as she walked to the door; that if she walked out the door, then you will have to...! If she proceeds to leave after being warned, then you can use all force necessary for theft. For what you see here, you can sue. A photo of the register itself is circumstantial. It does not prove any crime.