​Any gift valued above $2500 to a government official will be considered a gift to the country or state and will be required to be auctioned off.

And any items sold to government officials at below 50% of there retail price, would also be considered a gift and would be taxed at the full value.
In family gifts would be excluded. And if family members themselves received a large value gift and left that information off of their taxes they would also be held liable for tax fraud

If they want tips they should have gone into the service industry not public service. The offices of the United States are not for sale!