If you put 100 psi in the tires according to your pressure gauge then that's what you have. None of the TPMS systems are going to read exactly the same as the "gauged" pressure except by luck. But, they are close enough. What you are really looking for is variances and consistency in pressure changes as you drive. Don't worry about it.
Another thing. Gauge accuracy is all over the scale. I've seen differences of +/- 6-7 pounds when comparing the readings between a "quality" automotive gauge costing $50 or so vs a Tronair ASME TSO certified gauge costing nearly $400 (plus the annual cost of about $100 to certify accuracy). Close enough for our purposes. If you gauge them all at 100 psi then they are all the same. The "same" could be 97 psi or 104 psi.
If your TPMS started the day with all tires within five or so pounds of each other and they stay reasonably close to the variance then all is well. However, if you see five tires displaying 105 (or whatever) and the sixth one says 82 then it's time to pull over and find the problem. By pull over I mean as soon as it's safe to do so. It doesn't mean at the next exit 5-6 miles down the road.
At some point during every day you suddenly realize nothing else productive is going to happen the rest of that day. For me, it usually occurs around 9 am.
Vengeance 25V (the Harley needed a home)