You can't, unfortunately.
I live in SC and they are very open and honest about the odds for their scratch off games (though sometimes you won't believe it when you hit a losing streak! grrrrr.....).
However, though they post the total tickets in the run, the total prizes with the value of those prizes, and then even post the remaining top prizes for each ticket (and the dollar value of ALL prizes left), there's still no way to adjust the return/odds because we aren't given sales figures about how many total tickets have been sold.
Let's try to make this simple: As a ticket is sold, and prizes are won and losers are removed from the potential pool to buy from the odds do change. Unfortunately, we have no way of knowing what the new updated odds are.
It's even possible that ALL the top prizes could be gone from a ticket, and the ticket is still a GREAT ticket to play. But the only way to know that is to have access to a handful of very important current numbers, and all states keep at least one of those numbers to themselves so we can't determine which are the best tickets to currently play.
It will help if we simplify all the numbers, while keeping the principles the same. Let's pretend we have our own lottery, with a 20 ticket run for the whole set. In those twenty tickets (which we will sell for $1 a piece) we will have a single top prize of $5 and four smaller prizes of $2 a piece. This means that once we sell the entire reel of tickets we will have made $20 and have to pay out $13. This means our game has a return rate of 65% ($13/$20) which is a realistic return rate for a scratch off game.
We represent the tickets below, with dollar values for winners and the letter X for losers. We will divide them up into four groups as well to simulate that we are sending them out to four stores.
[X][X][X][X][$2]
[X][X][X][$2][X]
[X][$2][X][X][$2]
[X][X][$5][X][X]
Now, let's say that the game sells way down until the jackpot ($5) is won and we then have just these tickets left:
[$2]
[$2][X]
[X][$2]
Now, some might say that the jackpot is won, so this game is a waste of time. And true, the jackpot takes a large percentage of the prize with it once it's won, but because we can see everything, we can do the new math and see what the new return on this game is now....
$6 in prizes remaining, with $5 in total tickets left to buy. Thats' $6/$5, or 120% return!!!
When a game has a positive return (above 100%) that means it makes actual financial sense to buy as much of it as possible. Of course, this is a ultra rare situation, but even high returns below 100% still make for fun gambling.
But we can't know when these situations happen, because the states might as most tell us how much the value of the prizes are left. We wouldn't know (in our above scenario) that only 5 tickets were left with a value of $6.
So, concluding, without current sales data for tickets (how many have been sold, and how many prizes are left, and what the value is for the prizes remaining) we can't calculate current odds, and just have to rely on the odds they gave us when the ticket run started.