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	$155.71	5.374%	$164.0779	$164.08	$164.10	$164.10
Purchase #2	$29.54	5.796%	$31.2521	$31.25	$31.25	$31.30
Purchase #3	$214.97	10.723%	$238.0212	$238.02	$238.00	$238.00
Purchase #4	$175.60	7.472%	$188.7208	$188.72	$188.70	$188.70
Purchase #5	$207.29	10.763%	$229.6006	$229.60	$229.60	$229.60
Purchase #6	$153.39	8.531%	$166.4757	$166.48	$166.50	$166.50
Purchase #7	$150.64	7.818%	$162.417	$162.42	$162.40	$162.40
7 purchase totals =	$1,087.14		$1,180.5653	$1,180.57	$1,180.55	$1,180.60