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	$62.36	4.799%	$65.3527	$65.35	$65.35	$65.40
Purchase #2	$10.55	3.718%	$10.9422	$10.94	$10.95	$10.90
Purchase #3	$100.58	11.380%	$112.026	$112.03	$112.05	$112.00
Purchase #4	$120.64	6.333%	$128.2801	$128.28	$128.30	$128.30
Purchase #5	$47.35	13.456%	$53.7214	$53.72	$53.70	$53.70
Purchase #6	$179.91	6.549%	$191.6923	$191.69	$191.70	$191.70
Purchase #7	$157.57	6.519%	$167.842	$167.84	$167.85	$167.80
7 purchase totals =	$678.96		$729.8567	$729.85	$729.90	$729.80