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	$91.34	3.487%	$94.525	$94.53	$94.55	$94.50
Purchase #2	$237.58	5.511%	$250.673	$250.67	$250.65	$250.70
Purchase #3	$217.30	9.319%	$237.5502	$237.55	$237.55	$237.60
Purchase #4	$37.73	11.718%	$42.1512	$42.15	$42.15	$42.20
Purchase #5	$50.48	10.142%	$55.5997	$55.60	$55.60	$55.60
Purchase #6	$111.31	4.361%	$116.1642	$116.16	$116.15	$116.20
Purchase #7	$160.34	4.688%	$167.8567	$167.86	$167.85	$167.90
7 purchase totals =	$906.08		$964.5200	$964.52	$964.50	$964.70