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	$172.83	13.817%	$196.7099	$196.71	$196.70	$196.70
Purchase #2	$191.87	10.490%	$211.9972	$212.00	$212.00	$212.00
Purchase #3	$95.59	11.221%	$106.3162	$106.32	$106.30	$106.30
Purchase #4	$80.35	8.212%	$86.9483	$86.95	$86.95	$86.90
Purchase #5	$140.38	3.637%	$145.4856	$145.49	$145.50	$145.50
Purchase #6	$201.41	11.601%	$224.7756	$224.78	$224.80	$224.80
Purchase #7	$148.60	10.405%	$164.0618	$164.06	$164.05	$164.10
7 purchase totals =	$1,031.03		$1,136.2946	$1,136.31	$1,136.30	$1,136.30