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	$185.34	3.382%	$191.6082	$191.61	$191.60	$191.60
Purchase #2	$52.74	13.581%	$59.9026	$59.90	$59.90	$59.90
Purchase #3	$226.43	13.718%	$257.4917	$257.49	$257.50	$257.50
Purchase #4	$21.94	5.614%	$23.1717	$23.17	$23.15	$23.20
Purchase #5	$210.63	6.109%	$223.4974	$223.50	$223.50	$223.50
Purchase #6	$200.50	6.742%	$214.0177	$214.02	$214.00	$214.00
Purchase #7	$49.82	6.784%	$53.1998	$53.20	$53.20	$53.20
7 purchase totals =	$947.40		$1,022.8891	$1,022.89	$1,022.85	$1,022.90