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	$50.48	6.356%	$53.6885	$53.69	$53.70	$53.70
Purchase #2	$199.31	6.114%	$211.4958	$211.50	$211.50	$211.50
Purchase #3	$93.29	13.493%	$105.8776	$105.88	$105.90	$105.90
Purchase #4	$148.91	8.117%	$160.997	$161.00	$161.00	$161.00
Purchase #5	$190.91	6.581%	$203.4738	$203.47	$203.45	$203.50
Purchase #6	$10.38	9.740%	$11.391	$11.39	$11.40	$11.40
Purchase #7	$247.31	7.389%	$265.5837	$265.58	$265.60	$265.60
7 purchase totals =	$940.59		$1,012.5074	$1,012.51	$1,012.55	$1,012.60