From that article:

Not adjusting for inflation and differences in packaging sizes results in a higher total of $72.63.

So not adjusting the $1 coupon for inflation and not adjusting for things like the smallest TP package today being 6 rolls and the one in the movie being 4 rolls gets awfully close to (actually over) the number from the image.

Given you can't purchase partial container sizes at stores and coupons still tend to come in full dollar amount values including frequently $1 and don't have terms that adjust for inflation, I don't think one methodology here is inherently more correct than the other.