What was the connection between the Three-Fifths Compromise and taxes?
All tax or spending bills must originate in the house of representatives, The 3/5 compromise gave the south more influence and power on what taxes would be and how they were spent.
The House has control of the money ( according to the constitution.) The 3/5 compromise gave the south more representatives in the house and therefore more control over taxes. The south would have liked 5/5 of the slaves counted toward representation giving the south more control over how the taxes would be spent.
The north would have liked 0/5 slaves counted toward representation as the slaves could not vote for "their" representatives.
The 3/5 compromise gave the south enough control over taxes and spending that the southern colonies approved the new constitution.