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	$148.87	13.227%	$168.561	$168.56	$168.55	$168.60
Purchase #2	$13.93	4.401%	$14.5431	$14.54	$14.55	$14.50
Purchase #3	$37.75	7.181%	$40.4608	$40.46	$40.45	$40.50
Purchase #4	$38.90	13.604%	$44.192	$44.19	$44.20	$44.20
Purchase #5	$6.99	7.162%	$7.4906	$7.49	$7.50	$7.50
Purchase #6	$74.73	10.684%	$82.7142	$82.71	$82.70	$82.70
Purchase #7	$89.42	13.737%	$101.7036	$101.70	$101.70	$101.70
7 purchase totals =	$410.59		$459.6653	$459.65	$459.65	$459.70