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	$195.42	6.189%	$207.5145	$207.51	$207.50	$207.50
Purchase #2	$9.89	3.439%	$10.2301	$10.23	$10.25	$10.20
Purchase #3	$191.71	7.804%	$206.671	$206.67	$206.65	$206.70
Purchase #4	$56.62	4.538%	$59.1894	$59.19	$59.20	$59.20
Purchase #5	$215.62	4.786%	$225.9396	$225.94	$225.95	$225.90
Purchase #6	$225.71	12.458%	$253.829	$253.83	$253.85	$253.80
Purchase #7	$86.48	13.718%	$98.3433	$98.34	$98.35	$98.30
7 purchase totals =	$981.45		$1,061.7169	$1,061.71	$1,061.75	$1,061.60