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	$217.44	7.369%	$233.4632	$233.46	$233.45	$233.50
Purchase #2	$134.27	13.409%	$152.2743	$152.27	$152.25	$152.30
Purchase #3	$206.95	6.819%	$221.0619	$221.06	$221.05	$221.10
Purchase #4	$105.53	5.770%	$111.6191	$111.62	$111.60	$111.60
Purchase #5	$63.50	13.207%	$71.8864	$71.89	$71.90	$71.90
Purchase #6	$179.95	13.343%	$203.9607	$203.96	$203.95	$204.00
Purchase #7	$103.39	7.546%	$111.1918	$111.19	$111.20	$111.20
7 purchase totals =	$1,011.03		$1,105.4574	$1,105.45	$1,105.40	$1,105.60