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	$176.60	6.166%	$187.4892	$187.49	$187.50	$187.50
Purchase #2	$65.61	11.227%	$72.976	$72.98	$73.00	$73.00
Purchase #3	$200.49	7.620%	$215.7673	$215.77	$215.75	$215.80
Purchase #4	$84.79	12.176%	$95.114	$95.11	$95.10	$95.10
Purchase #5	$240.81	5.501%	$254.057	$254.06	$254.05	$254.10
Purchase #6	$34.60	12.800%	$39.0288	$39.03	$39.05	$39.00
Purchase #7	$176.67	11.141%	$196.3528	$196.35	$196.35	$196.40
7 purchase totals =	$979.57		$1,060.7851	$1,060.79	$1,060.80	$1,060.90