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	$61.78	5.335%	$65.076	$65.08	$65.10	$65.10
Purchase #2	$143.49	12.320%	$161.168	$161.17	$161.15	$161.20
Purchase #3	$167.79	3.839%	$174.2315	$174.23	$174.25	$174.20
Purchase #4	$218.96	10.560%	$242.0822	$242.08	$242.10	$242.10
Purchase #5	$230.37	11.185%	$256.1369	$256.14	$256.15	$256.10
Purchase #6	$63.47	13.504%	$72.041	$72.04	$72.05	$72.00
Purchase #7	$183.61	11.800%	$205.276	$205.28	$205.30	$205.30
7 purchase totals =	$1,069.47		$1,176.0116	$1,176.02	$1,176.10	$1,176.00