Ok I'll try to answer your question. Tavors use the same magazines as AR15s. Now there are lots of different AR magazines out there. The most common are aluminum bodied and typically called GI mags. They can only hold 5 rounds. There are also 10 round magazines, that have a very short body. These are typically labled as XCR or AR pistol mags. They are allowed to hold 10 rounds due to the rule that magazines designed specifically for a pistol are permitted to hold 10 rounds these magazines are only large enough to hold 10 rounds while most others are physically capable of holding more (usually 30) but are required by law to be restricted, usually with a rivet, to 5 rounds capacity.
Now it starts to get complicated. Somebody figured out that the law didn't say 5 rounds of 1 specific caliber. So since AR15s are available in a plethora of calibers somebody figured out that a magazine pinned to hold 5 rounds of .50 Beowulf ammunition, which is the physically largest caliber available in a normally functioning AR, would hold many more rounds of 5.56 yet still be legal under the Firearms Act. Consequently for people with AR15s, Tavors, and Robinson XCRs, all of which use the same magazines, these magazines have become very popular, since they usually hold around 15 rounds of 5.56.
The easiest magazines to find new for your rifle will likely be Magpul Pmags. But they will be restricted to 5 rounds unlike some of the other magazines listed. However they are easy to find and are usually available for under $30 per, which usually makes them the most affordable. New GI mags sometimes go on sale for under $20 a piece so they are worth scooping up when they come up, but they are also restricted to 5 rounds.
Hopefully this helps. It seems like reading comprehension has sunk to an all time low, here.