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	$86.70	8.831%	$94.3565	$94.36	$94.35	$94.40
Purchase #2	$205.29	11.243%	$228.3708	$228.37	$228.35	$228.40
Purchase #3	$89.89	4.716%	$94.1292	$94.13	$94.15	$94.10
Purchase #4	$100.56	13.473%	$114.1084	$114.11	$114.10	$114.10
Purchase #5	$84.40	6.816%	$90.1527	$90.15	$90.15	$90.20
Purchase #6	$239.41	13.386%	$271.4574	$271.46	$271.45	$271.50
Purchase #7	$167.88	10.598%	$185.6719	$185.67	$185.65	$185.70
7 purchase totals =	$974.13		$1,078.2469	$1,078.25	$1,078.20	$1,078.40