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	$187.37	4.873%	$196.5005	$196.50	$196.50	$196.50
Purchase #2	$172.69	5.112%	$181.5179	$181.52	$181.50	$181.50
Purchase #3	$68.76	8.803%	$74.8129	$74.81	$74.80	$74.80
Purchase #4	$132.88	7.636%	$143.0267	$143.03	$143.05	$143.00
Purchase #5	$109.27	7.439%	$117.3986	$117.40	$117.40	$117.40
Purchase #6	$211.82	10.766%	$234.6245	$234.62	$234.60	$234.60
Purchase #7	$68.53	4.165%	$71.3843	$71.38	$71.40	$71.40
7 purchase totals =	$951.32		$1,019.2654	$1,019.26	$1,019.25	$1,019.20