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	$94.95	11.145%	$105.5322	$105.53	$105.55	$105.50
Purchase #2	$151.32	6.577%	$161.2723	$161.27	$161.25	$161.30
Purchase #3	$229.61	3.163%	$236.8726	$236.87	$236.85	$236.90
Purchase #4	$28.79	9.324%	$31.4744	$31.47	$31.45	$31.50
Purchase #5	$77.61	6.427%	$82.598	$82.60	$82.60	$82.60
Purchase #6	$106.88	4.400%	$111.5827	$111.58	$111.60	$111.60
Purchase #7	$152.87	6.567%	$162.909	$162.91	$162.90	$162.90
7 purchase totals =	$842.03		$892.2412	$892.23	$892.20	$892.30