Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$86.40	10.457%	$95.4348	$95.43	$95.45	$95.40
Purchase #2	$191.65	11.383%	$213.4655	$213.47	$213.45	$213.50
Purchase #3	$164.62	12.701%	$185.5284	$185.53	$185.55	$185.50
Purchase #4	$202.70	6.542%	$215.9606	$215.96	$215.95	$216.00
Purchase #5	$188.25	6.680%	$200.8251	$200.83	$200.85	$200.80
Purchase #6	$158.31	7.418%	$170.0534	$170.05	$170.05	$170.10
Purchase #7	$126.61	13.695%	$143.9492	$143.95	$143.95	$143.90
7 purchase totals =	$1,118.54		$1,225.2170	$1,225.22	$1,225.25	$1,225.20