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	$200.77	6.103%	$213.023	$213.02	$213.00	$213.00
Purchase #2	$28.44	8.481%	$30.852	$30.85	$30.85	$30.90
Purchase #3	$71.48	10.279%	$78.8274	$78.83	$78.85	$78.80
Purchase #4	$199.54	5.127%	$209.7704	$209.77	$209.75	$209.80
Purchase #5	$151.25	5.221%	$159.1468	$159.15	$159.15	$159.10
Purchase #6	$91.93	7.768%	$99.0711	$99.07	$99.05	$99.10
Purchase #7	$204.95	11.218%	$227.9413	$227.94	$227.95	$227.90
7 purchase totals =	$948.36		$1,018.6320	$1,018.63	$1,018.60	$1,018.60