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	$51.62	5.309%	$54.3605	$54.36	$54.35	$54.40
Purchase #2	$147.36	6.284%	$156.6201	$156.62	$156.60	$156.60
Purchase #3	$110.26	11.602%	$123.0524	$123.05	$123.05	$123.10
Purchase #4	$143.91	7.469%	$154.6586	$154.66	$154.65	$154.70
Purchase #5	$204.48	4.602%	$213.8902	$213.89	$213.90	$213.90
Purchase #6	$88.47	3.779%	$91.8133	$91.81	$91.80	$91.80
Purchase #7	$205.91	7.699%	$221.763	$221.76	$221.75	$221.80
7 purchase totals =	$952.01		$1,016.1581	$1,016.15	$1,016.10	$1,016.30