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	$242.42	8.724%	$263.5687	$263.57	$263.55	$263.60
Purchase #2	$12.39	11.480%	$13.8124	$13.81	$13.80	$13.80
Purchase #3	$167.73	12.186%	$188.1696	$188.17	$188.15	$188.20
Purchase #4	$213.38	4.749%	$223.5134	$223.51	$223.50	$223.50
Purchase #5	$230.63	10.143%	$254.0228	$254.02	$254.00	$254.00
Purchase #6	$85.42	6.298%	$90.7998	$90.80	$90.80	$90.80
Purchase #7	$23.92	3.580%	$24.7763	$24.78	$24.80	$24.80
7 purchase totals =	$975.89		$1,058.6630	$1,058.66	$1,058.60	$1,058.70