Can my employer take money out of my check without my consent?

Monday January 5th, 2015 I work at subway and the way the system works is that if you don't make a cash drop (put money in the safe from the register) it won't let you ring people up. So during a lunch rush I made a cash drop for $100 dollars and a paper slip from the computer must be dropped with the money to prove you did the cash drop, but since we were busy I put the paper slip in the back counter and didn't touch the money and continued ringing people up then after that I got on the line and started helping make sandwiches and my manager started working the cash register. After a while my manager had to make another cash drop, so he made a $90 dollar one and dropped it. So then it came around to 2pm and I was almost about to go home for the day and before we leave we have to do a cash out (count the money,bread,flatbread,etc..) so I opened the register and saw a lot of $20 dollar bills so I made a cash drop of $100 dollars again and with the slip I stapled it and dropped it so after I finish counting the money, on the report of the cash out it said I was over $100 ( which is the first drop I was suppose to make but forgot about) so I told my manager that we were over $100 and he told me to just drop it in the safe and that the owner can figure it out. So I dropped it and clocked out. Then later that day the owner says he came into the store and grabbed money from the safe to get change for the night shift and that he took part of the money and deposited it in the bank. Wednesday January 7th, 2015 The owner came to count the cash drops for the week of 12/31/14-1/5/15 and Said there were $100 dollars missing from the safe and that it was the cash drop that I had done because he compared the time of cash drops on the slip to the end of the day report. I explained to him what happened and I told him that I didn't take the money and he could check the records in the cameras as you can clearly see I put the money in the safe as well as I had the manager as a witness that I put it in there and he proceeded to take $50 dollars out of my check with no warning. I'm pretty sure he will take the other $50 dollars out of my next paycheck and I can't afford that to happen.