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	$228.52	7.865%	$246.4931	$246.49	$246.50	$246.50
Purchase #2	$77.29	7.181%	$82.8402	$82.84	$82.85	$82.80
Purchase #3	$112.94	12.833%	$127.4336	$127.43	$127.45	$127.40
Purchase #4	$169.87	8.735%	$184.7081	$184.71	$184.70	$184.70
Purchase #5	$85.38	7.733%	$91.9824	$91.98	$92.00	$92.00
Purchase #6	$55.29	11.571%	$61.6876	$61.69	$61.70	$61.70
Purchase #7	$127.42	10.738%	$141.1024	$141.10	$141.10	$141.10
7 purchase totals =	$856.71		$936.2474	$936.24	$936.30	$936.20