Those tables in the DMG don't really work that well. I suggest taking a peek at the Magic Item Compendium, since it has completely different tables for rolling random treasure:
First, you roll a d20 and refer to the appropriate table (one per CR). The line you rolled shows you how many coins you roll for (the better your roll and the higher the CR, the higher the potential output.), what kind of good you roll for (those are gems and art), and what level of item you roll for.
Goods: They have designations from A to I or something. The higher the CR and the better you roll, the higher the rating of the good you get. The higher the rating, the more valuable the good (so you won't end up with a couple of 3 gp baubles for your CR 10 encounter, or with a 7000 gp diamond for your CR3 one, just because you rolled better). You just roll
Items: They're divided into levels (1-25 I think), and again, the higher the CR and your initial roll, the higher the level of the item you may get. You then refer to the appropriate table for that item level and roll. The items all have roughly the same value.
This all means that treasure is a lot less random: Before, minor, medium and major were awfully broad definitions - Major could mean some croll for a couple grand, or a near-artifact level super item for 200.000. The new system has many different levels with certain ranges of value depending on the "treasure rating", not just on the kind of item (no more tables you can get either a 10 gp or a 10.000 gp gem with the same roll, and so on).