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	$106.60	11.298%	$118.6437	$118.64	$118.65	$118.60
Purchase #2	$156.46	9.338%	$171.0702	$171.07	$171.05	$171.10
Purchase #3	$208.65	7.277%	$223.8335	$223.83	$223.85	$223.80
Purchase #4	$200.81	8.153%	$217.182	$217.18	$217.20	$217.20
Purchase #5	$94.29	4.362%	$98.4029	$98.40	$98.40	$98.40
Purchase #6	$48.69	4.624%	$50.9414	$50.94	$50.95	$50.90
Purchase #7	$248.86	9.452%	$272.3822	$272.38	$272.40	$272.40
7 purchase totals =	$1,064.36		$1,152.4559	$1,152.44	$1,152.50	$1,152.40