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	$59.82	9.202%	$65.3246	$65.32	$65.30	$65.30
Purchase #2	$33.67	11.175%	$37.4326	$37.43	$37.45	$37.40
Purchase #3	$73.94	7.323%	$79.3546	$79.35	$79.35	$79.40
Purchase #4	$49.91	9.643%	$54.7228	$54.72	$54.70	$54.70
Purchase #5	$131.31	11.237%	$146.0653	$146.07	$146.05	$146.10
Purchase #6	$238.37	6.412%	$253.6543	$253.65	$253.65	$253.70
Purchase #7	$82.94	9.554%	$90.8641	$90.86	$90.85	$90.90
7 purchase totals =	$669.96		$727.4183	$727.40	$727.35	$727.50