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	$127.46	4.698%	$133.4481	$133.45	$133.45	$133.40
Purchase #2	$60.57	3.575%	$62.7354	$62.74	$62.75	$62.70
Purchase #3	$179.27	6.322%	$190.6034	$190.60	$190.60	$190.60
Purchase #4	$179.67	4.498%	$187.7516	$187.75	$187.75	$187.80
Purchase #5	$80.39	12.155%	$90.1614	$90.16	$90.15	$90.20
Purchase #6	$182.84	12.366%	$205.45	$205.45	$205.45	$205.50
Purchase #7	$212.48	13.822%	$241.849	$241.85	$241.85	$241.80
7 purchase totals =	$1,022.68		$1,111.9989	$1,112.00	$1,112.00	$1,112.00