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	$177.28	7.545%	$190.6558	$190.66	$190.65	$190.70
Purchase #2	$248.53	3.229%	$256.555	$256.56	$256.55	$256.60
Purchase #3	$55.40	12.166%	$62.14	$62.14	$62.15	$62.10
Purchase #4	$210.87	3.428%	$218.0986	$218.10	$218.10	$218.10
Purchase #5	$165.41	5.599%	$174.6713	$174.67	$174.65	$174.70
Purchase #6	$104.42	6.488%	$111.1948	$111.19	$111.20	$111.20
Purchase #7	$188.85	7.536%	$203.0817	$203.08	$203.10	$203.10
7 purchase totals =	$1,150.76		$1,216.3972	$1,216.40	$1,216.40	$1,216.50