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	$241.37	10.695%	$267.1845	$267.18	$267.20	$267.20
Purchase #2	$116.86	8.733%	$127.0654	$127.07	$127.05	$127.10
Purchase #3	$248.79	5.427%	$262.2918	$262.29	$262.30	$262.30
Purchase #4	$72.48	12.375%	$81.4494	$81.45	$81.45	$81.40
Purchase #5	$57.81	4.489%	$60.4051	$60.41	$60.40	$60.40
Purchase #6	$77.53	6.153%	$82.3004	$82.30	$82.30	$82.30
Purchase #7	$124.58	5.663%	$131.635	$131.64	$131.65	$131.60
7 purchase totals =	$939.42		$1,012.3316	$1,012.34	$1,012.35	$1,012.30