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	$59.47	10.748%	$65.8618	$65.86	$65.85	$65.90
Purchase #2	$110.32	8.112%	$119.2692	$119.27	$119.25	$119.30
Purchase #3	$171.73	5.146%	$180.5672	$180.57	$180.55	$180.60
Purchase #4	$196.73	12.763%	$221.8386	$221.84	$221.85	$221.80
Purchase #5	$250.72	13.653%	$284.9508	$284.95	$284.95	$285.00
Purchase #6	$12.78	11.716%	$14.2773	$14.28	$14.30	$14.30
Purchase #7	$137.48	5.801%	$145.4552	$145.46	$145.45	$145.50
7 purchase totals =	$939.23		$1,032.2201	$1,032.23	$1,032.20	$1,032.40