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	$81.85	13.219%	$92.6698	$92.67	$92.65	$92.70
Purchase #2	$127.78	4.113%	$133.0356	$133.04	$133.05	$133.00
Purchase #3	$181.40	8.677%	$197.1401	$197.14	$197.15	$197.10
Purchase #4	$40.82	7.249%	$43.779	$43.78	$43.80	$43.80
Purchase #5	$78.78	4.442%	$82.2794	$82.28	$82.30	$82.30
Purchase #6	$157.72	11.694%	$176.1638	$176.16	$176.15	$176.20
Purchase #7	$128.36	11.827%	$143.5411	$143.54	$143.55	$143.50
7 purchase totals =	$796.71		$868.6088	$868.61	$868.65	$868.60