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	$13.39	11.618%	$14.9457	$14.95	$14.95	$14.90
Purchase #2	$62.74	8.179%	$67.8715	$67.87	$67.85	$67.90
Purchase #3	$77.64	5.735%	$82.0927	$82.09	$82.10	$82.10
Purchase #4	$22.89	8.819%	$24.9087	$24.91	$24.90	$24.90
Purchase #5	$59.67	9.168%	$65.1405	$65.14	$65.15	$65.10
Purchase #6	$172.51	5.450%	$181.9118	$181.91	$181.90	$181.90
Purchase #7	$219.41	3.611%	$227.3329	$227.33	$227.35	$227.30
7 purchase totals =	$628.25		$664.2038	$664.20	$664.20	$664.10