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	$127.96	7.728%	$137.8487	$137.85	$137.85	$137.80
Purchase #2	$47.68	7.702%	$51.3523	$51.35	$51.35	$51.40
Purchase #3	$32.79	10.756%	$36.3169	$36.32	$36.30	$36.30
Purchase #4	$38.72	4.333%	$40.3977	$40.40	$40.40	$40.40
Purchase #5	$35.92	5.119%	$37.7587	$37.76	$37.75	$37.80
Purchase #6	$146.84	4.589%	$153.5785	$153.58	$153.60	$153.60
Purchase #7	$216.87	12.630%	$244.2607	$244.26	$244.25	$244.30
7 purchase totals =	$646.78		$701.5135	$701.52	$701.50	$701.60