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	$126.95	11.242%	$141.2217	$141.22	$141.20	$141.20
Purchase #2	$183.66	11.643%	$205.0435	$205.04	$205.05	$205.00
Purchase #3	$42.49	9.331%	$46.4547	$46.45	$46.45	$46.50
Purchase #4	$204.34	5.468%	$215.5133	$215.51	$215.50	$215.50
Purchase #5	$43.75	4.231%	$45.6011	$45.60	$45.60	$45.60
Purchase #6	$159.47	5.600%	$168.4003	$168.40	$168.40	$168.40
Purchase #7	$216.53	3.613%	$224.3532	$224.35	$224.35	$224.40
7 purchase totals =	$977.19		$1,046.5878	$1,046.57	$1,046.55	$1,046.60