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	$114.27	4.462%	$119.3687	$119.37	$119.35	$119.40
Purchase #2	$140.82	3.346%	$145.5318	$145.53	$145.55	$145.50
Purchase #3	$211.65	5.383%	$223.0431	$223.04	$223.05	$223.00
Purchase #4	$71.91	5.822%	$76.0966	$76.10	$76.10	$76.10
Purchase #5	$137.95	5.543%	$145.5966	$145.60	$145.60	$145.60
Purchase #6	$74.54	10.452%	$82.3309	$82.33	$82.35	$82.30
Purchase #7	$157.32	10.357%	$173.6136	$173.61	$173.60	$173.60
7 purchase totals =	$908.46		$965.5813	$965.58	$965.60	$965.50