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	$118.44	7.540%	$127.3704	$127.37	$127.35	$127.40
Purchase #2	$183.67	4.218%	$191.4172	$191.42	$191.40	$191.40
Purchase #3	$25.39	7.626%	$27.3262	$27.33	$27.35	$27.30
Purchase #4	$66.45	7.327%	$71.3188	$71.32	$71.30	$71.30
Purchase #5	$43.50	7.752%	$46.8721	$46.87	$46.85	$46.90
Purchase #6	$227.40	4.612%	$237.8877	$237.89	$237.90	$237.90
Purchase #7	$37.30	8.624%	$40.5168	$40.52	$40.50	$40.50
7 purchase totals =	$702.15		$742.7092	$742.72	$742.65	$742.70