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	$216.25	3.145%	$223.0511	$223.05	$223.05	$223.10
Purchase #2	$216.66	4.872%	$227.2157	$227.22	$227.20	$227.20
Purchase #3	$47.43	13.402%	$53.7866	$53.79	$53.80	$53.80
Purchase #4	$62.61	13.398%	$70.9985	$71.00	$71.00	$71.00
Purchase #5	$230.40	8.732%	$250.5185	$250.52	$250.50	$250.50
Purchase #6	$172.84	10.864%	$191.6173	$191.62	$191.60	$191.60
Purchase #7	$83.96	3.103%	$86.5653	$86.57	$86.55	$86.60
7 purchase totals =	$1,030.15		$1,103.7530	$1,103.77	$1,103.70	$1,103.80