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	$215.72	11.864%	$241.313	$241.31	$241.30	$241.30
Purchase #2	$211.56	5.363%	$222.906	$222.91	$222.90	$222.90
Purchase #3	$172.32	12.791%	$194.3615	$194.36	$194.35	$194.40
Purchase #4	$209.93	4.221%	$218.7911	$218.79	$218.80	$218.80
Purchase #5	$97.61	10.461%	$107.821	$107.82	$107.80	$107.80
Purchase #6	$121.94	5.451%	$128.5869	$128.59	$128.60	$128.60
Purchase #7	$236.94	7.677%	$255.1299	$255.13	$255.15	$255.10
7 purchase totals =	$1,266.02		$1,368.9094	$1,368.91	$1,368.90	$1,368.90