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	$149.78	7.175%	$160.5267	$160.53	$160.55	$160.50
Purchase #2	$104.53	7.112%	$111.9642	$111.96	$111.95	$112.00
Purchase #3	$209.25	5.541%	$220.8445	$220.84	$220.85	$220.80
Purchase #4	$32.80	12.136%	$36.7806	$36.78	$36.80	$36.80
Purchase #5	$159.90	3.508%	$165.5093	$165.51	$165.50	$165.50
Purchase #6	$195.55	6.855%	$208.955	$208.96	$208.95	$209.00
Purchase #7	$127.77	11.149%	$142.0151	$142.02	$142.00	$142.00
7 purchase totals =	$979.58		$1,046.5954	$1,046.60	$1,046.60	$1,046.60