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	$182.75	7.387%	$196.2497	$196.25	$196.25	$196.20
Purchase #2	$64.50	5.248%	$67.885	$67.89	$67.90	$67.90
Purchase #3	$224.89	13.632%	$255.547	$255.55	$255.55	$255.50
Purchase #4	$88.50	8.675%	$96.1774	$96.18	$96.20	$96.20
Purchase #5	$76.65	5.428%	$80.8106	$80.81	$80.80	$80.80
Purchase #6	$182.35	6.258%	$193.7615	$193.76	$193.75	$193.80
Purchase #7	$226.52	13.821%	$257.8273	$257.83	$257.85	$257.80
7 purchase totals =	$1,046.16		$1,148.2585	$1,148.27	$1,148.30	$1,148.20