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	$58.53	5.174%	$61.5583	$61.56	$61.55	$61.60
Purchase #2	$42.35	5.516%	$44.686	$44.69	$44.70	$44.70
Purchase #3	$198.51	11.531%	$221.4002	$221.40	$221.40	$221.40
Purchase #4	$186.43	3.304%	$192.5896	$192.59	$192.60	$192.60
Purchase #5	$89.46	7.204%	$95.9047	$95.90	$95.90	$95.90
Purchase #6	$153.27	7.329%	$164.5032	$164.50	$164.50	$164.50
Purchase #7	$204.52	12.514%	$230.1136	$230.11	$230.10	$230.10
7 purchase totals =	$933.07		$1,010.7556	$1,010.75	$1,010.75	$1,010.80