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	$42.90	8.230%	$46.4307	$46.43	$46.45	$46.40
Purchase #2	$23.55	11.559%	$26.2721	$26.27	$26.25	$26.30
Purchase #3	$12.69	8.534%	$13.773	$13.77	$13.75	$13.80
Purchase #4	$238.59	13.719%	$271.3222	$271.32	$271.30	$271.30
Purchase #5	$131.31	4.607%	$137.3595	$137.36	$137.35	$137.40
Purchase #6	$181.97	10.398%	$200.8912	$200.89	$200.90	$200.90
Purchase #7	$34.56	8.745%	$37.5823	$37.58	$37.60	$37.60
7 purchase totals =	$665.57		$733.6310	$733.62	$733.60	$733.70