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	$91.41	7.688%	$98.4376	$98.44	$98.45	$98.40
Purchase #2	$62.46	4.452%	$65.2407	$65.24	$65.25	$65.20
Purchase #3	$227.50	3.650%	$235.8038	$235.80	$235.80	$235.80
Purchase #4	$83.78	5.534%	$88.4164	$88.42	$88.40	$88.40
Purchase #5	$153.90	13.314%	$174.3902	$174.39	$174.40	$174.40
Purchase #6	$158.61	5.386%	$167.1527	$167.15	$167.15	$167.20
Purchase #7	$172.31	7.724%	$185.6192	$185.62	$185.60	$185.60
7 purchase totals =	$949.97		$1,015.0606	$1,015.06	$1,015.05	$1,015.00