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	$230.96	4.617%	$241.6234	$241.62	$241.60	$241.60
Purchase #2	$72.79	13.302%	$82.4725	$82.47	$82.45	$82.50
Purchase #3	$140.35	4.448%	$146.5928	$146.59	$146.60	$146.60
Purchase #4	$50.47	7.212%	$54.1099	$54.11	$54.10	$54.10
Purchase #5	$187.59	10.844%	$207.9323	$207.93	$207.95	$207.90
Purchase #6	$226.57	6.628%	$241.5871	$241.59	$241.60	$241.60
Purchase #7	$34.46	7.246%	$36.957	$36.96	$36.95	$37.00
7 purchase totals =	$943.19		$1,011.2750	$1,011.27	$1,011.25	$1,011.30