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	$22.82	12.806%	$25.7423	$25.74	$25.75	$25.70
Purchase #2	$18.67	4.389%	$19.4894	$19.49	$19.50	$19.50
Purchase #3	$76.39	7.476%	$82.1009	$82.10	$82.10	$82.10
Purchase #4	$29.73	10.687%	$32.9072	$32.91	$32.90	$32.90
Purchase #5	$47.49	4.505%	$49.6294	$49.63	$49.65	$49.60
Purchase #6	$68.48	4.344%	$71.4548	$71.45	$71.45	$71.50
Purchase #7	$96.72	4.433%	$101.0076	$101.01	$101.00	$101.00
7 purchase totals =	$360.30		$382.3316	$382.33	$382.35	$382.30