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	$208.95	11.526%	$233.0336	$233.03	$233.05	$233.00
Purchase #2	$132.82	6.416%	$141.3417	$141.34	$141.35	$141.30
Purchase #3	$77.45	6.283%	$82.3162	$82.32	$82.30	$82.30
Purchase #4	$34.58	9.829%	$37.9789	$37.98	$38.00	$38.00
Purchase #5	$127.57	10.809%	$141.359	$141.36	$141.35	$141.40
Purchase #6	$244.62	4.138%	$254.7424	$254.74	$254.75	$254.70
Purchase #7	$242.40	4.513%	$253.3395	$253.34	$253.35	$253.30
7 purchase totals =	$1,068.39		$1,144.1113	$1,144.11	$1,144.15	$1,144.00