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	$85.33	12.495%	$95.992	$95.99	$96.00	$96.00
Purchase #2	$17.43	4.242%	$18.1694	$18.17	$18.15	$18.20
Purchase #3	$89.86	9.382%	$98.2907	$98.29	$98.30	$98.30
Purchase #4	$55.90	6.405%	$59.4804	$59.48	$59.50	$59.50
Purchase #5	$34.67	13.854%	$39.4732	$39.47	$39.45	$39.50
Purchase #6	$248.49	10.515%	$274.6187	$274.62	$274.60	$274.60
Purchase #7	$104.89	5.642%	$110.8079	$110.81	$110.80	$110.80
7 purchase totals =	$636.57		$696.8323	$696.83	$696.80	$696.90