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	$179.26	3.452%	$185.4481	$185.45	$185.45	$185.40
Purchase #2	$88.29	11.191%	$98.1705	$98.17	$98.15	$98.20
Purchase #3	$108.53	13.682%	$123.3791	$123.38	$123.40	$123.40
Purchase #4	$208.71	4.768%	$218.6613	$218.66	$218.65	$218.70
Purchase #5	$239.38	11.728%	$267.4545	$267.45	$267.45	$267.50
Purchase #6	$212.64	10.275%	$234.4888	$234.49	$234.50	$234.50
Purchase #7	$248.74	11.157%	$276.4919	$276.49	$276.50	$276.50
7 purchase totals =	$1,285.55		$1,404.0942	$1,404.09	$1,404.10	$1,404.20