My mage can now cast 5th level spells. Problem is, I can't find ANY, and all Orrick will offer me are the same tired old 1st-4th level scrolls. Having a couple of blanks in my memorized spells list really bites. Where in the game will I find some 5th level scrolls? I am now just beginning the Severed Hand.

I belive the reason you arent finding any higher level scrolls is... The game is designed with 7th level as the exp. limit.
Wizards at 7th level can only cast up to 4th level spells according to the paper and pencil AD&D rules. Your wizard should be at what 9th level or so to get his first 5th level spell? I am just taking an educated guess as to the reason the shops only supply scrolls useable by 7th level characters. If you want higher level spells you need to use Dale Keeper to get them.

You're thinking of Baldur's Gate, not IWD. A mage can reach 14th level, and use 7th level spells in IWD. And to the original poster, you start getting 5th level spells in the Severed Hand (I believe Animate Dead is the first you'll run across, remember to check all the stashes in the Hand!) and Dorn's Deep, so don't fret You don't get most of the 6th and 7th level spells till the very end of the game anyway.

-Wrath

You'll find them further into the quests, I can't buy any more decent scrolls form the guy in Kuldahar but I have found and written 5th and one 6th level spell. Can't memorise the 6th level spell yet.

Incidently my mage is a 10th level Conjuror.

orrick gets new spells as your advanture progresses. i think after the severed hand level is completed, orrick will get some new stuff for sale. sometimes random as to what he sells? i played thru a few times, and conse he offered me a red cloak of some sort?

Most of the high-level spells, 6th-9th, aren't going to be sold by Orrick. You'll find most of them in lower Dorn's Deep, from Malavon and Nym, as well as some barrels outside of Malavon's building, in the Artisan's District (where all the Umber Hulks and Blind Minotaurs are).

-Wrath

Seek out Bandoth in the first area of Upper Dorn's Deep for a few 5th level spells. You can also find a few scattered around the Severed Hand. Keep an eye peeled when you get to the third floor of the Severed Hands for a good source of spells and items....