I also say 95%.

All wrong so far, 95% seems reasonable when you do the maths, but you know it's wrong, as it would be 95% if you knew which pocket the ticket went in!!

I don't understand what this means.

Edit:

Upon further consideration, I'll change my answer to 90.48%.

Odds that I look in the correct pocket and they weren't tested: 2.5%

Odds that I look in the wrong pocket and they weren't tested: 2.5%

Odds that I look in the correct pocket and they were tested: 47.5%

Odds that I look in the wrong pocket and they were tested: 47.5%

I can rule out the third option (because that one would have resulted in me finding the tag). Looking at the remaining choices, the odds of the ticket being in the other pocket are 47.5%/(2.5%+2.5%) = 9.5 times greater than the odds of it not being in the other pocket. Remembering that the odds have to add up to 100% and doing some algebra, you can solve for the odds of the ticket being in the other pocket.

For everyone else who said 95% (as I initially did): Suppose the jeans have a billion pockets, and you look in all but the last one without finding the ticket - would you still say the odds are 95% that the ticket will be in that last pocket?