This is explicitly illegal under Federal labor law (FLSA, Fair Labor Standards Act). If you work at least half the day they can't dock you for it, period. Every instance they dock you for an hour is a breach of the law.

Here are the only situations in which a deduction may be made:

"Deductions from pay are permissible when an exempt em ployee: is absent from work for one or more full days for personal reasons other than sickness or disability; for absences of one or more full days due to sickness or disability if the deductio n is made in accordance w ith a bona fide plan, policy or practice of providing compensation for salary lost due to i llness; to offset amounts employees receive as jury or witness fees, or for military pay; for penalties imposed in good faith for infr actions of safety rules of major significance; or for unpaid disciplinary suspensions of one or more full da ys imposed in good faith fo r workplace conduct rule infractions. Also, an employer is not required to pay the full salary in the initial or terminal week of employment, or for weeks in which an exempt empl oyee takes unpaid leave under the Family and Medical Leave Act."

If they repeatedly do this, you may be entitled to backpay for all overtime worked while "salaried," as they are not treating you as a salaried employee, and thus will owe you the proper wages for your services.

"A reduction in salary that is inconsistent with these rules is considered an improper deduction. The practice of making improper deductions shows that an employer did not intend to pay employees on a "salary basis" and, therefore, disqualifies employees from the overtime exemption. An isolated or inadvertent improper deduction will not destroy the exemption if the employer reimburses the employee for the deduction. However, if the Department finds an actual practice of making improper deductions, all employees in the particular job classification subject to the deductions could lose their exempt status for the period during which deductions were made, even if some of those employees never had their own salaries reduced. Loss of the exemption would then subject the employer to liability for overtime compensation in addition to the salaries already paid. The employer could also face civil penalties for repeat or willful overtime violations."