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	$230.51	10.768%	$255.3313	$255.33	$255.35	$255.30
Purchase #2	$119.98	3.826%	$124.5704	$124.57	$124.55	$124.60
Purchase #3	$50.71	11.802%	$56.6948	$56.69	$56.70	$56.70
Purchase #4	$149.92	9.740%	$164.5222	$164.52	$164.50	$164.50
Purchase #5	$133.46	13.570%	$151.5705	$151.57	$151.55	$151.60
Purchase #6	$208.82	8.696%	$226.979	$226.98	$227.00	$227.00
Purchase #7	$42.66	5.712%	$45.0967	$45.10	$45.10	$45.10
7 purchase totals =	$936.06		$1,024.7649	$1,024.76	$1,024.75	$1,024.80