$25/niece or nephew/Christmas and birthday.
We thankfully ended the adult sibling exchanges.
My H spends between $25-$50 on his parents for Christmas and birthdays.
I spend around $50/parent for birthday gifts, we ended the adult exchange there as well for Christmas.
I'd love to cut the adult exchanging entirely, particularly the Christmas with my ILs because the whole thing is stupid, but they pitched an epic fit when my H suggested it.
No, this has not changed as our income increased. In fact, we spend less on the ILs now because my H has been very disappointed in their behavior around gifts and is over it.