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	$53.31	11.399%	$59.3868	$59.39	$59.40	$59.40
Purchase #2	$97.82	12.284%	$109.8362	$109.84	$109.85	$109.80
Purchase #3	$146.53	5.454%	$154.5217	$154.52	$154.50	$154.50
Purchase #4	$205.29	10.523%	$226.8927	$226.89	$226.90	$226.90
Purchase #5	$170.39	10.685%	$188.5962	$188.60	$188.60	$188.60
Purchase #6	$217.37	13.586%	$246.9019	$246.90	$246.90	$246.90
Purchase #7	$176.42	6.248%	$187.4427	$187.44	$187.45	$187.40
7 purchase totals =	$1,067.13		$1,173.5782	$1,173.58	$1,173.60	$1,173.50