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	$194.80	7.571%	$209.5483	$209.55	$209.55	$209.50
Purchase #2	$68.90	13.471%	$78.1815	$78.18	$78.20	$78.20
Purchase #3	$48.60	6.809%	$51.9092	$51.91	$51.90	$51.90
Purchase #4	$200.33	7.407%	$215.1684	$215.17	$215.15	$215.20
Purchase #5	$199.31	6.559%	$212.3827	$212.38	$212.40	$212.40
Purchase #6	$190.85	13.281%	$216.1968	$216.20	$216.20	$216.20
Purchase #7	$158.44	8.723%	$172.2607	$172.26	$172.25	$172.30
7 purchase totals =	$1,061.23		$1,155.6476	$1,155.65	$1,155.65	$1,155.70