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	$194.32	5.870%	$205.7266	$205.73	$205.75	$205.70
Purchase #2	$161.87	7.347%	$173.7626	$173.76	$173.75	$173.80
Purchase #3	$112.69	9.404%	$123.2874	$123.29	$123.30	$123.30
Purchase #4	$152.78	5.858%	$161.7299	$161.73	$161.75	$161.70
Purchase #5	$27.85	12.357%	$31.2914	$31.29	$31.30	$31.30
Purchase #6	$99.74	12.348%	$112.0559	$112.06	$112.05	$112.10
Purchase #7	$63.66	6.401%	$67.7349	$67.73	$67.75	$67.70
7 purchase totals =	$812.91		$875.5887	$875.59	$875.65	$875.60