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	$234.64	8.564%	$254.7346	$254.73	$254.75	$254.70
Purchase #2	$130.95	10.356%	$144.5112	$144.51	$144.50	$144.50
Purchase #3	$47.78	4.151%	$49.7633	$49.76	$49.75	$49.80
Purchase #4	$21.78	7.764%	$23.471	$23.47	$23.45	$23.50
Purchase #5	$246.49	3.670%	$255.5362	$255.54	$255.55	$255.50
Purchase #6	$86.61	7.117%	$92.774	$92.77	$92.75	$92.80
Purchase #7	$223.52	7.671%	$240.6662	$240.67	$240.65	$240.70
7 purchase totals =	$991.77		$1,061.4565	$1,061.45	$1,061.40	$1,061.50