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	$71.72	4.117%	$74.6727	$74.67	$74.65	$74.70
Purchase #2	$204.46	4.475%	$213.6096	$213.61	$213.60	$213.60
Purchase #3	$15.61	6.663%	$16.6501	$16.65	$16.65	$16.70
Purchase #4	$144.60	13.540%	$164.1788	$164.18	$164.20	$164.20
Purchase #5	$87.77	3.524%	$90.863	$90.86	$90.85	$90.90
Purchase #6	$33.56	10.507%	$37.0861	$37.09	$37.10	$37.10
Purchase #7	$96.32	4.250%	$100.4136	$100.41	$100.40	$100.40
7 purchase totals =	$654.04		$697.4739	$697.47	$697.45	$697.60