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	$117.49	11.223%	$130.6759	$130.68	$130.70	$130.70
Purchase #2	$18.45	6.571%	$19.6623	$19.66	$19.65	$19.70
Purchase #3	$203.63	10.858%	$225.7401	$225.74	$225.75	$225.70
Purchase #4	$182.90	4.661%	$191.425	$191.43	$191.45	$191.40
Purchase #5	$176.87	4.795%	$185.3509	$185.35	$185.35	$185.40
Purchase #6	$164.96	4.197%	$171.8834	$171.88	$171.90	$171.90
Purchase #7	$83.65	7.333%	$89.7841	$89.78	$89.80	$89.80
7 purchase totals =	$947.95		$1,014.5217	$1,014.52	$1,014.60	$1,014.60