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	$68.88	3.244%	$71.1145	$71.11	$71.10	$71.10
Purchase #2	$101.29	8.665%	$110.0668	$110.07	$110.05	$110.10
Purchase #3	$14.82	4.643%	$15.5081	$15.51	$15.50	$15.50
Purchase #4	$170.33	7.268%	$182.7096	$182.71	$182.70	$182.70
Purchase #5	$9.80	8.197%	$10.6033	$10.60	$10.60	$10.60
Purchase #6	$140.82	3.615%	$145.9106	$145.91	$145.90	$145.90
Purchase #7	$174.89	12.341%	$196.4732	$196.47	$196.45	$196.50
7 purchase totals =	$680.83		$732.3861	$732.38	$732.30	$732.40