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	$155.82	4.320%	$162.5514	$162.55	$162.55	$162.60
Purchase #2	$51.43	6.365%	$54.7035	$54.70	$54.70	$54.70
Purchase #3	$118.69	7.667%	$127.79	$127.79	$127.80	$127.80
Purchase #4	$141.25	7.112%	$151.2957	$151.30	$151.30	$151.30
Purchase #5	$47.91	6.339%	$50.947	$50.95	$50.95	$50.90
Purchase #6	$94.59	8.649%	$102.7711	$102.77	$102.75	$102.80
Purchase #7	$217.58	7.342%	$233.5547	$233.55	$233.55	$233.60
7 purchase totals =	$827.27		$883.6134	$883.61	$883.60	$883.70