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	$211.59	10.157%	$233.0812	$233.08	$233.10	$233.10
Purchase #2	$190.41	12.268%	$213.7695	$213.77	$213.75	$213.80
Purchase #3	$250.46	9.167%	$273.4197	$273.42	$273.40	$273.40
Purchase #4	$242.92	12.485%	$273.2486	$273.25	$273.25	$273.20
Purchase #5	$30.74	12.294%	$34.5192	$34.52	$34.50	$34.50
Purchase #6	$211.89	10.181%	$233.4625	$233.46	$233.45	$233.50
Purchase #7	$206.72	7.683%	$222.6023	$222.60	$222.60	$222.60
7 purchase totals =	$1,344.73		$1,484.1030	$1,484.10	$1,484.05	$1,484.10