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	$231.39	9.751%	$253.9528	$253.95	$253.95	$254.00
Purchase #2	$46.69	7.188%	$50.0461	$50.05	$50.05	$50.00
Purchase #3	$67.55	5.319%	$71.143	$71.14	$71.15	$71.10
Purchase #4	$139.73	12.671%	$157.4352	$157.44	$157.45	$157.40
Purchase #5	$82.78	3.804%	$85.929	$85.93	$85.95	$85.90
Purchase #6	$156.87	10.187%	$172.8503	$172.85	$172.85	$172.90
Purchase #7	$239.91	5.669%	$253.5105	$253.51	$253.50	$253.50
7 purchase totals =	$964.92		$1,044.8669	$1,044.87	$1,044.90	$1,044.80