The cash amounts of the taxes were not particularly high, but to the colonist's eyes this was besides the point. The success of the French and Indian war was enabled by a cooperation between the colonial governments and the British military. When a campaign was required, General Redcoat would go to a colonial legislature and say 'we need 500 men and their equipment, and supplies for 3 weeks. Or even "I need 10000 pounds to pay the regulars" Then the legislature would take care of the raising of the troops, supplies and funds. So the government and colonial government were partners in the enterprise of winning the war for the king.
Then after the war, the British Laws come in and cut out the colonial governments entirely, without even consulting them. By American colonial thinking, Parliament should have sent a message to the 13 colonies asking them to raise X dollars for this purpose. And after some negotiation, presumably they would do it. Parliament, having had nothing to do with the previous arrangement aside from benefiting from it, saw no need to elevate the status of colonial governments into a kind of partners in the Empire, decided to play hardball. The Colonial governments, not wanting to be demoted to bystanders, fought back with boycotts and later more extreme actions. And when push came to shove, the Colonies won independence. It all might have been avoided with some understanding on both sides of the ocean, but that's the breaks.