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	$40.30	10.419%	$44.4989	$44.50	$44.50	$44.50
Purchase #2	$177.74	11.806%	$198.724	$198.72	$198.70	$198.70
Purchase #3	$177.26	7.194%	$190.0121	$190.01	$190.00	$190.00
Purchase #4	$223.31	13.646%	$253.7829	$253.78	$253.80	$253.80
Purchase #5	$10.54	9.595%	$11.5513	$11.55	$11.55	$11.60
Purchase #6	$174.64	4.201%	$181.9766	$181.98	$182.00	$182.00
Purchase #7	$170.83	11.526%	$190.5199	$190.52	$190.50	$190.50
7 purchase totals =	$974.62		$1,071.0657	$1,071.06	$1,071.05	$1,071.10