Need help understanding my APR & minimum payment calculation

[figi419]

We have a jewelry store card with a "21% APR & 1.75% MPR" with a balance of $2489.  The monthly minimum payment is $155.  I'm guessing part of the minimum payment is a $15 monthly insurance fee.

My question is that I don't understand how they calculate the minimum payment. We have a small chunk of money we are wanting to put down on one of our lines of credit and were trying to see what the new monthly payments would be on each. 

This one stumps us however. We have lines with a larger balance and higher APR but this line has double the minimum payment. We are using the BankRate.com calculators.  Just trying to figure out why & how. 

Thank you!

[Anonymous]

It might help others answer the questions if you could tell us the name of the jewelry store. Kay? Jared?

Looking at the Kay Jeweler's website (I just chose Kay at random), I see that in the terms and conditions they state that the minimum payment will be at least $25. Then they have a table for the minimum payments based on a range of balances:

$1,500.01 to $2,500.00 = 6% of Highest Regular Balance

So, since your balance is within that range, if you had a Kay Jewelers card (and all other jewelers that roll up into the Kay family) that your minimum payment is based off of 6%. 6% of $2,489 is $149.34. So they rounded up to the next whole number + $5 as described here:

"The minimum payment for your regular balance will be calculated as follows, except any minimum payment in excess of $25.00 will be rounded up to the nearest $5.00 increment, and the minimum payment for your regular balance will never exceed the Regular Balance"

http://www.kay.com/ContentView?catalogId=10001&langId=-1&storeId=10101&cmsId=general_terms_and_condi...

So I would guess this is what is happening in your case. 6% minimum of $2,489, rounded up to the next whole dollar + $5:  $149.34 -> $150.00 + $5 = $155.