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	$74.76	10.563%	$82.6569	$82.66	$82.65	$82.70
Purchase #2	$203.83	3.571%	$211.1088	$211.11	$211.10	$211.10
Purchase #3	$114.27	11.545%	$127.4625	$127.46	$127.45	$127.50
Purchase #4	$160.64	12.180%	$180.206	$180.21	$180.20	$180.20
Purchase #5	$205.53	12.616%	$231.4597	$231.46	$231.45	$231.50
Purchase #6	$191.96	11.424%	$213.8895	$213.89	$213.90	$213.90
Purchase #7	$111.83	9.718%	$122.6976	$122.70	$122.70	$122.70
7 purchase totals =	$1,062.82		$1,169.4810	$1,169.49	$1,169.45	$1,169.60