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	$164.82	5.351%	$173.6395	$173.64	$173.65	$173.60
Purchase #2	$227.82	5.821%	$241.0814	$241.08	$241.10	$241.10
Purchase #3	$97.56	8.228%	$105.5872	$105.59	$105.60	$105.60
Purchase #4	$27.92	5.282%	$29.3947	$29.39	$29.40	$29.40
Purchase #5	$168.50	13.843%	$191.8255	$191.83	$191.85	$191.80
Purchase #6	$60.41	12.220%	$67.7921	$67.79	$67.80	$67.80
Purchase #7	$192.94	13.429%	$218.8499	$218.85	$218.85	$218.80
7 purchase totals =	$939.97		$1,028.1703	$1,028.17	$1,028.25	$1,028.10