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	$224.56	4.538%	$234.7505	$234.75	$234.75	$234.80
Purchase #2	$6.82	8.630%	$7.4086	$7.41	$7.40	$7.40
Purchase #3	$56.27	6.358%	$59.8476	$59.85	$59.85	$59.80
Purchase #4	$239.55	7.656%	$257.8899	$257.89	$257.90	$257.90
Purchase #5	$93.42	13.610%	$106.1345	$106.13	$106.15	$106.10
Purchase #6	$211.73	6.787%	$226.1001	$226.10	$226.10	$226.10
Purchase #7	$174.27	11.663%	$194.5951	$194.60	$194.60	$194.60
7 purchase totals =	$1,006.62		$1,086.7263	$1,086.73	$1,086.75	$1,086.70