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	$214.74	7.397%	$230.6243	$230.62	$230.60	$230.60
Purchase #2	$159.40	10.354%	$175.9043	$175.90	$175.90	$175.90
Purchase #3	$223.75	3.205%	$230.9212	$230.92	$230.90	$230.90
Purchase #4	$181.44	10.760%	$200.9629	$200.96	$200.95	$201.00
Purchase #5	$68.83	5.462%	$72.5895	$72.59	$72.60	$72.60
Purchase #6	$78.60	5.665%	$83.0527	$83.05	$83.05	$83.10
Purchase #7	$106.89	3.650%	$110.7915	$110.79	$110.80	$110.80
7 purchase totals =	$1,033.65		$1,104.8464	$1,104.83	$1,104.80	$1,104.90