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	$216.83	12.558%	$244.0595	$244.06	$244.05	$244.10
Purchase #2	$77.59	8.484%	$84.1727	$84.17	$84.15	$84.20
Purchase #3	$55.37	13.220%	$62.6899	$62.69	$62.70	$62.70
Purchase #4	$39.49	8.624%	$42.8956	$42.90	$42.90	$42.90
Purchase #5	$211.54	9.148%	$230.8917	$230.89	$230.90	$230.90
Purchase #6	$167.28	3.160%	$172.566	$172.57	$172.55	$172.60
Purchase #7	$200.89	11.431%	$223.8537	$223.85	$223.85	$223.90
7 purchase totals =	$968.99		$1,061.1291	$1,061.13	$1,061.10	$1,061.30