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	$87.79	11.433%	$97.827	$97.83	$97.85	$97.80
Purchase #2	$101.82	9.458%	$111.4501	$111.45	$111.45	$111.50
Purchase #3	$168.97	9.470%	$184.9715	$184.97	$184.95	$185.00
Purchase #4	$40.82	12.563%	$45.9482	$45.95	$45.95	$45.90
Purchase #5	$76.55	5.536%	$80.7878	$80.79	$80.80	$80.80
Purchase #6	$69.90	6.459%	$74.4148	$74.41	$74.40	$74.40
Purchase #7	$120.25	9.710%	$131.9263	$131.93	$131.95	$131.90
7 purchase totals =	$666.10		$727.3257	$727.33	$727.35	$727.30