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	$242.28	4.780%	$253.861	$253.86	$253.85	$253.90
Purchase #2	$65.92	9.618%	$72.2602	$72.26	$72.25	$72.30
Purchase #3	$200.64	9.729%	$220.1603	$220.16	$220.15	$220.20
Purchase #4	$78.61	10.388%	$86.776	$86.78	$86.80	$86.80
Purchase #5	$113.64	10.259%	$125.2983	$125.30	$125.30	$125.30
Purchase #6	$239.71	6.628%	$255.598	$255.60	$255.60	$255.60
Purchase #7	$189.89	5.250%	$199.8592	$199.86	$199.85	$199.90
7 purchase totals =	$1,130.69		$1,213.8130	$1,213.82	$1,213.80	$1,214.00