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	$40.73	13.290%	$46.143	$46.14	$46.15	$46.10
Purchase #2	$93.94	8.495%	$101.9202	$101.92	$101.90	$101.90
Purchase #3	$172.69	7.519%	$185.6746	$185.67	$185.65	$185.70
Purchase #4	$244.94	10.146%	$269.7916	$269.79	$269.80	$269.80
Purchase #5	$230.90	6.327%	$245.509	$245.51	$245.50	$245.50
Purchase #6	$196.85	9.793%	$216.1275	$216.13	$216.15	$216.10
Purchase #7	$12.64	5.209%	$13.2984	$13.30	$13.30	$13.30
7 purchase totals =	$992.69		$1,078.4643	$1,078.46	$1,078.45	$1,078.40