Yes, it is the rule:
5-12-2: "Time-outs in excess of the allotted number may be requested
and shall be granted . . . at the expense of a technical foul for each.
Does your partner also officiate football? In basketball, we only "ignore" a time-out request in a few circumstances:
- live ball, the requesting team doesn't have control.
- when requested before a foul has been reported.
- before the opening jump ball.
- if it's a successive time-out at the end of the 4th quarter/OT.