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	$207.73	3.725%	$215.4679	$215.47	$215.45	$215.50
Purchase #2	$27.33	4.648%	$28.6003	$28.60	$28.60	$28.60
Purchase #3	$99.97	11.379%	$111.3456	$111.35	$111.35	$111.30
Purchase #4	$54.52	5.245%	$57.3796	$57.38	$57.40	$57.40
Purchase #5	$93.75	3.584%	$97.11	$97.11	$97.10	$97.10
Purchase #6	$205.37	5.370%	$216.3984	$216.40	$216.40	$216.40
Purchase #7	$190.79	12.289%	$214.2362	$214.24	$214.25	$214.20
7 purchase totals =	$879.46		$940.5380	$940.55	$940.55	$940.50