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	$153.30	5.616%	$161.9093	$161.91	$161.90	$161.90
Purchase #2	$20.25	7.548%	$21.7785	$21.78	$21.80	$21.80
Purchase #3	$157.76	11.153%	$175.355	$175.36	$175.35	$175.40
Purchase #4	$177.73	10.502%	$196.3952	$196.40	$196.40	$196.40
Purchase #5	$31.53	9.276%	$34.4547	$34.45	$34.45	$34.50
Purchase #6	$68.60	5.535%	$72.397	$72.40	$72.40	$72.40
Purchase #7	$131.68	6.423%	$140.1378	$140.14	$140.15	$140.10
7 purchase totals =	$740.85		$802.4275	$802.44	$802.45	$802.50