I understand that under Virginia Labor laws that "tipped" employees are those who make more than $20.00 in tips and are allowed to be paid $2.13 an hour. I also understand that if they do not average $5.85 and hour the company/restaurant is suppose to reimburse them to atleast minimum wage, or $5.85.

My question : How long does this $2.13 + tips count for. For example, restaurant has corporate coming in, and want to be super clean. Servers last tipping table leaves at 8:00 PM, and they will not be given any more tables by order of management for the night. They comeplete "normal" side work within an hour. "Normal" being the amount of work given on an average shift. Than, because corporate is coming in tommorrow, from 9 pm to 12 am they assign "extra" cleaning, as in cleaning walls, floor, pictures, counters and kitchen ware, all at $2.13 hour. The servers average is still above minimum all night, including the 3 hours of extra work.

I guess im wondering how far a restaurant is allowed to broaden their work given to servers, and does it go by tips + $2.13 an hour, or does it average out on a shift.

See Dual Jobs here.
http://www.dol.gov/esa/regs/compliance/whd/whdfs15.pdf

Since this extra time appears to be basically janitorial work, not the standard "side work" that servers often perform, I would opine that the DOL would say that the three hours spent cleaning must be paid at the full minimum wage.