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	$175.94	8.509%	$190.9107	$190.91	$190.90	$190.90
Purchase #2	$31.34	8.565%	$34.0243	$34.02	$34.00	$34.00
Purchase #3	$6.31	5.800%	$6.676	$6.68	$6.70	$6.70
Purchase #4	$95.32	11.405%	$106.1912	$106.19	$106.20	$106.20
Purchase #5	$86.64	10.225%	$95.4989	$95.50	$95.50	$95.50
Purchase #6	$52.69	3.403%	$54.483	$54.48	$54.50	$54.50
Purchase #7	$145.89	13.370%	$165.3955	$165.40	$165.40	$165.40
7 purchase totals =	$594.13		$653.1796	$653.18	$653.20	$653.20