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	$171.64	11.535%	$191.4387	$191.44	$191.45	$191.40
Purchase #2	$48.41	10.821%	$53.6484	$53.65	$53.65	$53.60
Purchase #3	$39.76	4.682%	$41.6216	$41.62	$41.60	$41.60
Purchase #4	$111.30	6.449%	$118.4777	$118.48	$118.50	$118.50
Purchase #5	$98.99	12.712%	$111.5736	$111.57	$111.55	$111.60
Purchase #6	$95.80	12.823%	$108.0844	$108.08	$108.10	$108.10
Purchase #7	$72.93	4.782%	$76.4175	$76.42	$76.40	$76.40
7 purchase totals =	$638.83		$701.2619	$701.26	$701.25	$701.20