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	$104.53	6.146%	$110.9544	$110.95	$110.95	$111.00
Purchase #2	$173.64	13.278%	$196.6959	$196.70	$196.70	$196.70
Purchase #3	$60.28	3.387%	$62.3217	$62.32	$62.30	$62.30
Purchase #4	$170.79	7.432%	$183.4831	$183.48	$183.50	$183.50
Purchase #5	$106.77	4.753%	$111.8448	$111.84	$111.85	$111.80
Purchase #6	$190.34	13.818%	$216.6412	$216.64	$216.65	$216.60
Purchase #7	$129.56	7.116%	$138.7795	$138.78	$138.80	$138.80
7 purchase totals =	$935.91		$1,020.7206	$1,020.71	$1,020.75	$1,020.70