Do not keep toilet paper at the reference desk. It's tacky. Toilet paper is for use at the toilet. The reference desk can be bad, but it's no toilet. Class things up a bit by buying a generic box of Kleenex. The ones in the floral box. If you really want to show the patrons that you care, splurge and get the ones with lotion.
Are you crafty? Crochet a Kleenex-cozy to keep those tissues warm and comfortable. Just be sure to color coordinate it with your library's decor. Nothing ruins a good nose-blow like a mismatched tissue-box cover.