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	$245.37	7.156%	$262.9287	$262.93	$262.95	$262.90
Purchase #2	$54.72	4.339%	$57.0943	$57.09	$57.10	$57.10
Purchase #3	$99.31	5.842%	$105.1117	$105.11	$105.10	$105.10
Purchase #4	$55.92	3.151%	$57.682	$57.68	$57.70	$57.70
Purchase #5	$84.81	5.523%	$89.4941	$89.49	$89.50	$89.50
Purchase #6	$129.57	10.107%	$142.6656	$142.67	$142.65	$142.70
Purchase #7	$217.86	13.624%	$247.5412	$247.54	$247.55	$247.50
7 purchase totals =	$887.56		$962.5176	$962.51	$962.55	$962.50