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	$106.42	4.517%	$111.227	$111.23	$111.25	$111.20
Purchase #2	$107.39	4.344%	$112.055	$112.06	$112.05	$112.10
Purchase #3	$194.80	11.873%	$217.9286	$217.93	$217.95	$217.90
Purchase #4	$135.60	10.690%	$150.0956	$150.10	$150.10	$150.10
Purchase #5	$63.54	13.234%	$71.9489	$71.95	$71.95	$71.90
Purchase #6	$222.27	5.509%	$234.5149	$234.51	$234.50	$234.50
Purchase #7	$119.66	4.809%	$125.4144	$125.41	$125.40	$125.40
7 purchase totals =	$949.68		$1,023.1844	$1,023.19	$1,023.20	$1,023.10