Common core breaks down when you have to involve writing down the steps due to the size of the operands and there ordinary algorithms shine.
When faced with $20 - $14.45, I round up the $14.45 to $15 and subtract from $20. I have $5. Now, I think how much more I still have and that is $0.55. I add them together to get $5.55.
If I can write the answer, why would you dock points just because my way of doing this simple math is inefficient?
Common core is not about efficiency, it's about helping kids develop an intuitive understanding of how numbers work.
It turns out that a lot of children who learned how to subtract on paper with borrowing never learn how to do math in their head the way you described. Common core is an attempt to correct that deficiency.