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	$48.40	7.391%	$51.9772	$51.98	$52.00	$52.00
Purchase #2	$56.47	7.263%	$60.5714	$60.57	$60.55	$60.60
Purchase #3	$149.59	6.238%	$158.9214	$158.92	$158.90	$158.90
Purchase #4	$245.57	5.688%	$259.538	$259.54	$259.55	$259.50
Purchase #5	$205.25	5.135%	$215.7896	$215.79	$215.80	$215.80
Purchase #6	$53.46	4.638%	$55.9395	$55.94	$55.95	$55.90
Purchase #7	$229.28	4.103%	$238.6874	$238.69	$238.70	$238.70
7 purchase totals =	$988.02		$1,041.4245	$1,041.43	$1,041.45	$1,041.40