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	$196.25	11.572%	$218.9601	$218.96	$218.95	$219.00
Purchase #2	$111.33	9.711%	$122.1413	$122.14	$122.15	$122.10
Purchase #3	$151.93	12.287%	$170.5976	$170.60	$170.60	$170.60
Purchase #4	$133.83	12.416%	$150.4463	$150.45	$150.45	$150.40
Purchase #5	$183.31	7.105%	$196.3342	$196.33	$196.35	$196.30
Purchase #6	$183.77	3.632%	$190.4445	$190.44	$190.45	$190.40
Purchase #7	$180.94	3.243%	$186.8079	$186.81	$186.80	$186.80
7 purchase totals =	$1,141.36		$1,235.7319	$1,235.73	$1,235.75	$1,235.60