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	$158.35	5.834%	$167.5881	$167.59	$167.60	$167.60
Purchase #2	$60.72	7.444%	$65.24	$65.24	$65.25	$65.20
Purchase #3	$151.52	6.216%	$160.9385	$160.94	$160.95	$160.90
Purchase #4	$221.54	10.565%	$244.9457	$244.95	$244.95	$244.90
Purchase #5	$188.59	4.338%	$196.771	$196.77	$196.75	$196.80
Purchase #6	$86.31	4.585%	$90.2673	$90.27	$90.25	$90.30
Purchase #7	$175.66	13.731%	$199.7799	$199.78	$199.80	$199.80
7 purchase totals =	$1,042.69		$1,125.5305	$1,125.54	$1,125.55	$1,125.50