I used to work at one of the TJX stores and had to try to get people to sign up for this card.
From what I remember, at one point they had an option on our screen to check whether the customer was interested in applying for the Mastercard or not. It wasn't originally an option but at some point they added it. So it may be possible to apply for just the store card and not the Mastercard, if that interests you for some reason. I don't think you can only apply for the Mastercard without applying for the store card at the same time (e.g. if you're denied the Mastercard, I think they automatically check to see if you can be approved for the store card).
The vast majority of people I signed up got either $500 or $1000 limits. Most people were approved, but obviously that's anecdotal.
I believe it's backed by GE. It used to be Chase.
Unless they've changed something, it's $10 for every $200 you spend at TJ Maxx, Marshalls, and HomeGoods (not per $100 like OP stated). 10% off first purchase when you get approved. Even if you're not approved, depending on the day/manager, they might still give you the 10% for applying. If you get the Mastercard, it's $10 for every $1000 you spend outside of TJX stores. Basically you earn 1 point for non-TJX purchases and 5 points for TJX purchases and when you get to 1000 points you get a gift certificate.
BofA Cash Rewards 25,000 (2009) | Citi Double Cash 25,000 (2011) | Cap1 Quicksilver 10,000 (2013) | Discover It 31,000 (2014) | Chase Freedom 9000 (2014) | Barclaycard Rewards 25,000 (2014)
FICO: 840 Discover/Barclays/BofA TU, 869 Citi Equifax
