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	$44.46	4.745%	$46.5696	$46.57	$46.55	$46.60
Purchase #2	$245.63	4.832%	$257.4988	$257.50	$257.50	$257.50
Purchase #3	$35.91	11.801%	$40.1477	$40.15	$40.15	$40.10
Purchase #4	$183.60	13.513%	$208.4099	$208.41	$208.40	$208.40
Purchase #5	$206.27	7.857%	$222.4766	$222.48	$222.50	$222.50
Purchase #6	$197.59	10.788%	$218.906	$218.91	$218.90	$218.90
Purchase #7	$67.78	8.323%	$73.4213	$73.42	$73.40	$73.40
7 purchase totals =	$981.24		$1,067.4299	$1,067.44	$1,067.40	$1,067.40