Deductions for time off from commission

If you have an employment agreement which specificies that there may be deductions from commissions for time off, then yes. (And an "agreement" in this context might also include term sheets, an employee handbook, or other piece of writing putting you on notice of the fact that there are deductions for missed time.) So the first question is, what is the company's written policy and/or what agreements do you have with them.

However, in the absence of such a piece of writing, then no: commissions are earned as a % of sale and have no relation to hours worked--if you sold X dollars, you earn Y commissions. The "penalty" for taking time off is that you are not selling and ergo not making money.

Indeed, even an hourly wage cannot be "docked" for time off--you simply don't earn money for period not working.

Only if you are on a base salary (exempt income) and take unpaid time off can you employer dock your salary for the days you're away. Do you receive a base salary (again, not an hourly wage) and is that what your employer is actually charging the time against?

Finally, note that if you have not yet earned time off, your employer may possibly terminate you for taking "unpaid"--i.e. unearned--time unless it was specifically approved by a supervisor. Taking time off unless you have either vacation or leave time to use, or unless it's approved by a supervisor, can be considered absenteeism.