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	$73.54	3.408%	$76.0462	$76.05	$76.05	$76.00
Purchase #2	$199.47	13.124%	$225.6484	$225.65	$225.65	$225.60
Purchase #3	$241.33	12.447%	$271.3683	$271.37	$271.35	$271.40
Purchase #4	$12.75	7.400%	$13.6935	$13.69	$13.70	$13.70
Purchase #5	$206.63	7.706%	$222.5529	$222.55	$222.55	$222.60
Purchase #6	$112.67	5.502%	$118.8691	$118.87	$118.85	$118.90
Purchase #7	$76.76	4.749%	$80.4053	$80.41	$80.40	$80.40
7 purchase totals =	$923.15		$1,008.5837	$1,008.59	$1,008.55	$1,008.60