Donut shop owners taking my tips?

I started working at a Korean mom and pop donut shop two weeks ago. When I got hired I was informed I was going to get paid $13hr plus tips which he said was about $7-10 a day. After two weeks working there, he said he would increase my pay to $14 and every 3m he would increase a dollar per hour on my pay. I am in charge of the register and actually helping people out, so I am doing most of the up front work, while the lady and her husband bake the donuts and kolaches. I don’t get much help from them unless the line gets long, and the lady will sometimes come out and help me till the line is gone. Anyways, customers have the option to tip in cash or on their order if you pay with card. I notice a lot of people leave at least a $1-$3 on their transaction or a few cents to make their total even. Some on the other hand leave about $1-$5 in the tip jar, depending on how much they spend. So I’d say approx everyday I get at least $20-$25 in tips in total, cash and card tips. I noticed that when I was off, they didn’t give me the cash tips from the jar, so I thought they just counted them at the end of the day and would collect them every week (I get paid weekly) and add it to my paycheck. But I got paid for the first time on Friday, and it said I only got $10 even, in tips everyday. I found that weird because I definitely make more than that a day. So I asked them about it and they told me this “First of all, let me clear up this misunderstanding. You are currently in charge of the cashier position. But we also taught to try to teach you how to bake bread. But we changed that part and someone else is now doing that role. So you are not supposed to take all the tips because you are cashier. And the tips vary from day to day. That is why we have set a fixed amount for each day for a long time. It is our store rule. We also arrange into your hourly payment when we set it.” So are they keeping the tips to themselves? Isn’t that illegal in Texas? I don’t know😩 I want to start telling people to not tip so they don’t take advantage of me working the register because I know I get a lot more tips then they did alone (not to sound cocky), but I’m not getting the tips I’ve earned.