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	$119.42	3.234%	$123.282	$123.28	$123.30	$123.30
Purchase #2	$15.75	12.294%	$17.6863	$17.69	$17.70	$17.70
Purchase #3	$6.90	7.204%	$7.3971	$7.40	$7.40	$7.40
Purchase #4	$148.91	13.311%	$168.7314	$168.73	$168.75	$168.70
Purchase #5	$133.31	12.832%	$150.4163	$150.42	$150.40	$150.40
Purchase #6	$185.71	10.129%	$204.5206	$204.52	$204.50	$204.50
Purchase #7	$95.56	6.622%	$101.888	$101.89	$101.90	$101.90
7 purchase totals =	$705.56		$773.9217	$773.93	$773.95	$773.90