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	$148.61	3.550%	$153.8857	$153.89	$153.90	$153.90
Purchase #2	$47.72	6.674%	$50.9048	$50.90	$50.90	$50.90
Purchase #3	$160.52	5.408%	$169.2009	$169.20	$169.20	$169.20
Purchase #4	$143.55	11.677%	$160.3123	$160.31	$160.30	$160.30
Purchase #5	$216.74	10.615%	$239.747	$239.75	$239.75	$239.70
Purchase #6	$160.44	7.787%	$172.9335	$172.93	$172.95	$172.90
Purchase #7	$62.90	3.412%	$65.0461	$65.05	$65.05	$65.00
7 purchase totals =	$940.48		$1,012.0303	$1,012.03	$1,012.05	$1,011.90