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	$172.67	11.161%	$191.9417	$191.94	$191.95	$191.90
Purchase #2	$84.99	13.672%	$96.6098	$96.61	$96.60	$96.60
Purchase #3	$85.27	6.683%	$90.9686	$90.97	$90.95	$91.00
Purchase #4	$81.31	5.509%	$85.7894	$85.79	$85.80	$85.80
Purchase #5	$169.26	9.264%	$184.9402	$184.94	$184.95	$184.90
Purchase #6	$160.66	8.864%	$174.9009	$174.90	$174.90	$174.90
Purchase #7	$192.45	9.119%	$209.9995	$210.00	$210.00	$210.00
7 purchase totals =	$946.61		$1,035.1501	$1,035.15	$1,035.15	$1,035.10