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	$244.95	8.260%	$265.1829	$265.18	$265.20	$265.20
Purchase #2	$248.61	4.249%	$259.1734	$259.17	$259.15	$259.20
Purchase #3	$48.27	13.420%	$54.7478	$54.75	$54.75	$54.70
Purchase #4	$160.80	7.103%	$172.2216	$172.22	$172.20	$172.20
Purchase #5	$193.56	6.641%	$206.4143	$206.41	$206.40	$206.40
Purchase #6	$51.71	11.477%	$57.6448	$57.64	$57.65	$57.60
Purchase #7	$167.94	10.287%	$185.216	$185.22	$185.20	$185.20
7 purchase totals =	$1,115.84		$1,200.6008	$1,200.59	$1,200.55	$1,200.50