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	$105.67	5.852%	$111.8538	$111.85	$111.85	$111.90
Purchase #2	$53.48	3.251%	$55.2186	$55.22	$55.20	$55.20
Purchase #3	$33.50	7.169%	$35.9016	$35.90	$35.90	$35.90
Purchase #4	$172.98	10.648%	$191.3989	$191.40	$191.40	$191.40
Purchase #5	$193.80	11.352%	$215.8002	$215.80	$215.80	$215.80
Purchase #6	$128.57	5.707%	$135.9075	$135.91	$135.90	$135.90
Purchase #7	$245.85	11.248%	$273.5032	$273.50	$273.50	$273.50
7 purchase totals =	$933.85		$1,019.5838	$1,019.58	$1,019.55	$1,019.60