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	$205.41	4.223%	$214.0845	$214.08	$214.10	$214.10
Purchase #2	$73.72	11.323%	$82.0673	$82.07	$82.05	$82.10
Purchase #3	$82.42	13.253%	$93.3431	$93.34	$93.35	$93.30
Purchase #4	$248.46	11.452%	$276.9136	$276.91	$276.90	$276.90
Purchase #5	$113.38	12.242%	$127.26	$127.26	$127.25	$127.30
Purchase #6	$207.75	7.511%	$223.3541	$223.35	$223.35	$223.40
Purchase #7	$18.71	9.370%	$20.4631	$20.46	$20.45	$20.50
7 purchase totals =	$949.85		$1,037.4857	$1,037.47	$1,037.45	$1,037.60