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	$72.37	13.237%	$81.9496	$81.95	$81.95	$81.90
Purchase #2	$199.37	10.390%	$220.0845	$220.08	$220.10	$220.10
Purchase #3	$234.69	13.405%	$266.1502	$266.15	$266.15	$266.20
Purchase #4	$80.92	5.332%	$85.2347	$85.23	$85.25	$85.20
Purchase #5	$98.86	12.788%	$111.5022	$111.50	$111.50	$111.50
Purchase #6	$213.95	10.346%	$236.0853	$236.09	$236.10	$236.10
Purchase #7	$54.31	12.112%	$60.888	$60.89	$60.90	$60.90
7 purchase totals =	$954.47		$1,061.8945	$1,061.89	$1,061.95	$1,061.90