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	$155.78	10.802%	$172.6074	$172.61	$172.60	$172.60
Purchase #2	$196.62	10.488%	$217.2415	$217.24	$217.25	$217.20
Purchase #3	$53.35	5.551%	$56.3115	$56.31	$56.30	$56.30
Purchase #4	$15.55	7.162%	$16.6637	$16.66	$16.65	$16.70
Purchase #5	$198.37	12.429%	$223.0254	$223.03	$223.05	$223.00
Purchase #6	$29.98	11.218%	$33.3432	$33.34	$33.35	$33.30
Purchase #7	$206.39	13.564%	$234.3847	$234.38	$234.40	$234.40
7 purchase totals =	$856.04		$953.5774	$953.57	$953.60	$953.50