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	$196.66	7.234%	$210.8864	$210.89	$210.90	$210.90
Purchase #2	$20.73	10.382%	$22.8822	$22.88	$22.90	$22.90
Purchase #3	$48.88	3.550%	$50.6152	$50.62	$50.60	$50.60
Purchase #4	$130.87	13.504%	$148.5427	$148.54	$148.55	$148.50
Purchase #5	$146.49	9.584%	$160.5296	$160.53	$160.55	$160.50
Purchase #6	$181.60	5.190%	$191.025	$191.03	$191.05	$191.00
Purchase #7	$29.96	7.702%	$32.2675	$32.27	$32.25	$32.30
7 purchase totals =	$755.19		$816.7486	$816.76	$816.80	$816.70