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	$205.54	11.204%	$228.5687	$228.57	$228.55	$228.60
Purchase #2	$67.29	5.802%	$71.1942	$71.19	$71.20	$71.20
Purchase #3	$63.40	6.616%	$67.5945	$67.59	$67.60	$67.60
Purchase #4	$242.78	7.312%	$260.5321	$260.53	$260.55	$260.50
Purchase #5	$133.54	7.433%	$143.466	$143.47	$143.45	$143.50
Purchase #6	$179.53	12.847%	$202.5942	$202.59	$202.60	$202.60
Purchase #7	$89.69	11.156%	$99.6958	$99.70	$99.70	$99.70
7 purchase totals =	$981.77		$1,073.6455	$1,073.64	$1,073.65	$1,073.70