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	$234.58	4.681%	$245.5607	$245.56	$245.55	$245.60
Purchase #2	$9.78	8.403%	$10.6018	$10.60	$10.60	$10.60
Purchase #3	$73.55	6.800%	$78.5514	$78.55	$78.55	$78.60
Purchase #4	$14.25	8.239%	$15.4241	$15.42	$15.40	$15.40
Purchase #5	$93.33	5.814%	$98.7562	$98.76	$98.75	$98.80
Purchase #6	$35.76	12.735%	$40.314	$40.31	$40.30	$40.30
Purchase #7	$226.79	4.644%	$237.3221	$237.32	$237.30	$237.30
7 purchase totals =	$688.04		$726.5303	$726.52	$726.45	$726.60