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	$218.48	8.800%	$237.7062	$237.71	$237.70	$237.70
Purchase #2	$92.83	8.341%	$100.573	$100.57	$100.55	$100.60
Purchase #3	$222.45	7.108%	$238.2617	$238.26	$238.25	$238.30
Purchase #4	$226.53	8.325%	$245.3886	$245.39	$245.40	$245.40
Purchase #5	$74.39	10.423%	$82.1437	$82.14	$82.15	$82.10
Purchase #6	$89.44	13.227%	$101.2702	$101.27	$101.25	$101.30
Purchase #7	$184.78	10.838%	$204.8065	$204.81	$204.80	$204.80
7 purchase totals =	$1,108.90		$1,210.1499	$1,210.15	$1,210.10	$1,210.20