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	$157.50	4.725%	$164.9419	$164.94	$164.95	$164.90
Purchase #2	$209.58	4.696%	$219.4219	$219.42	$219.40	$219.40
Purchase #3	$51.91	11.342%	$57.7976	$57.80	$57.80	$57.80
Purchase #4	$8.59	3.111%	$8.8572	$8.86	$8.85	$8.90
Purchase #5	$5.66	9.231%	$6.1825	$6.18	$6.20	$6.20
Purchase #6	$189.69	4.166%	$197.5925	$197.59	$197.60	$197.60
Purchase #7	$99.89	5.778%	$105.6616	$105.66	$105.65	$105.70
7 purchase totals =	$722.82		$760.4552	$760.45	$760.45	$760.50