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	$176.25	11.210%	$196.0076	$196.01	$196.00	$196.00
Purchase #2	$44.72	3.165%	$46.1354	$46.14	$46.15	$46.10
Purchase #3	$40.68	13.777%	$46.2845	$46.28	$46.30	$46.30
Purchase #4	$215.46	6.420%	$229.2925	$229.29	$229.30	$229.30
Purchase #5	$183.84	10.105%	$202.417	$202.42	$202.40	$202.40
Purchase #6	$86.60	3.407%	$89.5505	$89.55	$89.55	$89.60
Purchase #7	$87.69	13.851%	$99.8359	$99.84	$99.85	$99.80
7 purchase totals =	$835.24		$909.5234	$909.53	$909.55	$909.50