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	$68.43	4.815%	$71.7249	$71.72	$71.70	$71.70
Purchase #2	$90.62	3.150%	$93.4745	$93.47	$93.45	$93.50
Purchase #3	$39.83	5.538%	$42.0358	$42.04	$42.05	$42.00
Purchase #4	$40.57	8.614%	$44.0647	$44.06	$44.05	$44.10
Purchase #5	$217.47	13.583%	$247.009	$247.01	$247.00	$247.00
Purchase #6	$169.67	6.383%	$180.5	$180.50	$180.50	$180.50
Purchase #7	$46.30	13.140%	$52.3838	$52.38	$52.40	$52.40
7 purchase totals =	$672.89		$731.1927	$731.18	$731.15	$731.20