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	$130.83	13.704%	$148.7589	$148.76	$148.75	$148.80
Purchase #2	$35.55	7.362%	$38.1672	$38.17	$38.15	$38.20
Purchase #3	$103.86	7.773%	$111.933	$111.93	$111.95	$111.90
Purchase #4	$209.27	11.248%	$232.8087	$232.81	$232.80	$232.80
Purchase #5	$167.62	5.303%	$176.5089	$176.51	$176.50	$176.50
Purchase #6	$248.59	4.549%	$259.8984	$259.90	$259.90	$259.90
Purchase #7	$63.92	3.362%	$66.069	$66.07	$66.05	$66.10
7 purchase totals =	$959.64		$1,034.1441	$1,034.15	$1,034.10	$1,034.20