Employer keeps last paycheque due to suspected stealing

My wife started working for a local distillery in March as part of a co-op program for her university course.

She goes to farmers markets to sell their products and has started making friends with other vendors at these markets. She was recently told by another vendor that her boss is infamous for claiming that his employees steal his product and then keeping their final paycheques whenever they decide to leave. It is important to note that he claims he has not fired anyone in the last year, but has had 10+ employees quit, so he is waiting for these people to quit and then deciding that they stole and keeping their final paycheques. My wife ended up reaching out to one of the other employees at the distillery to see if there is any truth to these claims and it turns out that it is all true.

The issue is that my wife plans to quiet in early August and she has started to notice her employer doing things that could make it seem like she stole. She has accidentally broken three bottles at a market (she took pictures of the broken bottles) and her boss told her not to worry, no need to pay for them and to just delete the pictures and forget about it, but then a week later he brought up that the money she earned does not match the amount of product. She mentioned the broken bottles which he “forgot about”. Then a few weeks after that he gave her more product but a few of the boxes were missing bottles, I was with her as she opened the boxes so I saw that, so she messaged him about it and he said that was his mistake and just work around it. Again, a week later he messaged her and claimed that her product does not match the amount of money earned, she is “missing bottles”, so she has to remind him that he did not give her as much as usual but he started saying that he gave her the same as always.

My wife is really worried that when she quits he will say she stole product and keep her final paycheque.

Can her employer legally keep her final paycheque when she quits if he claims that she stole product?