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	$41.92	8.394%	$45.4388	$45.44	$45.45	$45.40
Purchase #2	$71.75	9.690%	$78.7026	$78.70	$78.70	$78.70
Purchase #3	$11.54	9.167%	$12.5979	$12.60	$12.60	$12.60
Purchase #4	$238.69	3.784%	$247.722	$247.72	$247.70	$247.70
Purchase #5	$131.45	10.280%	$144.9631	$144.96	$144.95	$145.00
Purchase #6	$30.48	3.744%	$31.6212	$31.62	$31.60	$31.60
Purchase #7	$247.41	3.689%	$256.537	$256.54	$256.55	$256.50
7 purchase totals =	$773.24		$817.5826	$817.58	$817.55	$817.50