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	$196.52	9.385%	$214.9634	$214.96	$214.95	$215.00
Purchase #2	$247.93	13.589%	$281.6212	$281.62	$281.60	$281.60
Purchase #3	$148.42	12.179%	$166.4961	$166.50	$166.50	$166.50
Purchase #4	$221.79	7.690%	$238.8457	$238.85	$238.85	$238.80
Purchase #5	$95.96	9.201%	$104.7893	$104.79	$104.80	$104.80
Purchase #6	$9.35	11.392%	$10.4152	$10.42	$10.40	$10.40
Purchase #7	$89.62	5.109%	$94.1987	$94.20	$94.20	$94.20
7 purchase totals =	$1,009.59		$1,111.3296	$1,111.34	$1,111.30	$1,111.30