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	$62.94	4.641%	$65.861	$65.86	$65.85	$65.90
Purchase #2	$17.71	8.366%	$19.1916	$19.19	$19.20	$19.20
Purchase #3	$189.67	3.523%	$196.3521	$196.35	$196.35	$196.40
Purchase #4	$232.73	5.329%	$245.1322	$245.13	$245.15	$245.10
Purchase #5	$169.98	8.797%	$184.9331	$184.93	$184.95	$184.90
Purchase #6	$79.85	6.558%	$85.0866	$85.09	$85.10	$85.10
Purchase #7	$204.95	8.267%	$221.8932	$221.89	$221.90	$221.90
7 purchase totals =	$957.83		$1,018.4498	$1,018.44	$1,018.50	$1,018.50