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	$7.68	3.429%	$7.9433	$7.94	$7.95	$7.90
Purchase #2	$53.68	11.679%	$59.9493	$59.95	$59.95	$59.90
Purchase #3	$118.97	5.819%	$125.8929	$125.89	$125.90	$125.90
Purchase #4	$131.52	5.250%	$138.4248	$138.42	$138.40	$138.40
Purchase #5	$93.31	6.746%	$99.6047	$99.60	$99.60	$99.60
Purchase #6	$197.83	3.818%	$205.3831	$205.38	$205.40	$205.40
Purchase #7	$72.52	5.514%	$76.5188	$76.52	$76.50	$76.50
7 purchase totals =	$675.51		$713.7169	$713.70	$713.70	$713.60