Is selling vouchers that represent transportation fares permissible with a deduction for the office's commission, knowing that the value of the voucher and its payment date are known, or is this considered usury?

It is not permissible to give the driver what is in the check because it is an exchange (sarf) where the receipt of one of its countervalues is delayed, and in sarf, there must be mutual possession (taqabud) in the same session, in addition to the element of gharar (uncertainty) involved. The permissible alternative is to agree with the driver to collect the value of the check in exchange for a known fare, then pay him the value after it has been collected.