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	$54.78	11.604%	$61.1367	$61.14	$61.15	$61.10
Purchase #2	$61.39	9.246%	$67.0661	$67.07	$67.05	$67.10
Purchase #3	$208.70	5.347%	$219.8592	$219.86	$219.85	$219.90
Purchase #4	$88.47	3.442%	$91.5151	$91.52	$91.50	$91.50
Purchase #5	$70.65	10.815%	$78.2908	$78.29	$78.30	$78.30
Purchase #6	$58.70	3.488%	$60.7475	$60.75	$60.75	$60.70
Purchase #7	$110.43	5.445%	$116.4429	$116.44	$116.45	$116.40
7 purchase totals =	$653.12		$695.0583	$695.07	$695.05	$695.00