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	$212.33	10.529%	$234.6862	$234.69	$234.70	$234.70
Purchase #2	$172.25	11.171%	$191.492	$191.49	$191.50	$191.50
Purchase #3	$144.27	5.487%	$152.1861	$152.19	$152.20	$152.20
Purchase #4	$44.54	3.748%	$46.2094	$46.21	$46.20	$46.20
Purchase #5	$158.65	10.595%	$175.459	$175.46	$175.45	$175.50
Purchase #6	$26.76	11.679%	$29.8853	$29.89	$29.90	$29.90
Purchase #7	$243.58	9.602%	$266.9686	$266.97	$266.95	$267.00
7 purchase totals =	$1,002.38		$1,096.8866	$1,096.90	$1,096.90	$1,097.00