But we used to figure everything to the half cent. That's my point. We stopped figuring it to the half cent when we got rid of the half cent coin.
In the same way, we would stop figuring things to the whole cent if we got rid of the penny.
As an example, let's say I wanted to buy an item that was $1.75, but it was 50% off. How much does that cost? In reality, it should be $0.875, but we don't track to the half penny, so we just call it 88¢.
Or, if you buy something for $1.50, but there's a sales tax of 3%, that item will be $1.545 after sales tax, but they just round it to $1.55.
They're already rounding your numbers up. That's already happening. The only reason it feels different is because we "don't track fractional pennies," which is only true because we got rid of the coins that allowed us to track fractional pennies.
If we got rid of the coins that let us track individual pennies, we would also stop tracking all exchanges to the individual penny, and simply round to the nearest 5¢.
Which, in many cases, could actually work in your favor, I might add. If you bought something and the total was 1.52, they would simply round it down to $1.50. Sales tax law varies state to state, but that it's how the vast majority of states handle fractional pennies already, so precident indicates it would be that way for rounding to the nearest 5¢. E.g. if sales tax is 2%, and you bought something for $1.19, that comes out to $1.2138, but most states round that to $1.21, saving you 0.38¢ (38 one hundredths of a cent).