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	$227.33	7.602%	$244.6116	$244.61	$244.60	$244.60
Purchase #2	$143.75	4.407%	$150.0851	$150.09	$150.10	$150.10
Purchase #3	$64.92	8.283%	$70.2973	$70.30	$70.30	$70.30
Purchase #4	$19.65	12.443%	$22.095	$22.10	$22.10	$22.10
Purchase #5	$198.71	9.104%	$216.8006	$216.80	$216.80	$216.80
Purchase #6	$242.45	13.656%	$275.559	$275.56	$275.55	$275.60
Purchase #7	$36.25	9.242%	$39.6002	$39.60	$39.60	$39.60
7 purchase totals =	$933.06		$1,019.0488	$1,019.06	$1,019.05	$1,019.10