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	$195.54	10.863%	$216.7815	$216.78	$216.80	$216.80
Purchase #2	$108.46	13.801%	$123.4286	$123.43	$123.45	$123.40
Purchase #3	$122.65	13.832%	$139.6149	$139.61	$139.60	$139.60
Purchase #4	$174.54	6.245%	$185.44	$185.44	$185.45	$185.40
Purchase #5	$184.62	5.677%	$195.1009	$195.10	$195.10	$195.10
Purchase #6	$48.72	5.765%	$51.5287	$51.53	$51.55	$51.50
Purchase #7	$179.79	11.181%	$199.8923	$199.89	$199.90	$199.90
7 purchase totals =	$1,014.32		$1,111.7869	$1,111.78	$1,111.85	$1,111.70