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	$230.25	10.191%	$253.7148	$253.71	$253.70	$253.70
Purchase #2	$146.80	10.509%	$162.2272	$162.23	$162.25	$162.20
Purchase #3	$94.80	9.267%	$103.5851	$103.59	$103.60	$103.60
Purchase #4	$173.45	13.401%	$196.694	$196.69	$196.70	$196.70
Purchase #5	$64.31	12.697%	$72.4754	$72.48	$72.50	$72.50
Purchase #6	$136.57	3.116%	$140.8255	$140.83	$140.85	$140.80
Purchase #7	$178.39	13.318%	$202.148	$202.15	$202.15	$202.10
7 purchase totals =	$1,024.57		$1,131.6700	$1,131.68	$1,131.75	$1,131.60