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	$49.44	7.548%	$53.1717	$53.17	$53.15	$53.20
Purchase #2	$11.83	5.707%	$12.5051	$12.51	$12.50	$12.50
Purchase #3	$77.69	13.630%	$88.2791	$88.28	$88.30	$88.30
Purchase #4	$183.78	6.377%	$195.4997	$195.50	$195.50	$195.50
Purchase #5	$59.47	4.374%	$62.0712	$62.07	$62.05	$62.10
Purchase #6	$82.71	8.191%	$89.4848	$89.48	$89.50	$89.50
Purchase #7	$205.31	5.381%	$216.3577	$216.36	$216.35	$216.40
7 purchase totals =	$670.23		$717.3693	$717.37	$717.35	$717.50