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	$162.51	7.105%	$174.0563	$174.06	$174.05	$174.10
Purchase #2	$42.99	3.445%	$44.471	$44.47	$44.45	$44.50
Purchase #3	$244.68	4.532%	$255.7689	$255.77	$255.75	$255.80
Purchase #4	$9.46	11.103%	$10.5103	$10.51	$10.50	$10.50
Purchase #5	$203.92	6.375%	$216.9199	$216.92	$216.90	$216.90
Purchase #6	$163.54	5.248%	$172.1226	$172.12	$172.10	$172.10
Purchase #7	$220.60	13.165%	$249.642	$249.64	$249.65	$249.60
7 purchase totals =	$1,047.70		$1,123.4910	$1,123.49	$1,123.40	$1,123.50