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	$44.85	10.227%	$49.4368	$49.44	$49.45	$49.40
Purchase #2	$43.59	13.136%	$49.316	$49.32	$49.30	$49.30
Purchase #3	$119.45	9.670%	$131.0008	$131.00	$131.00	$131.00
Purchase #4	$215.39	8.479%	$233.6529	$233.65	$233.65	$233.70
Purchase #5	$200.32	11.567%	$223.491	$223.49	$223.50	$223.50
Purchase #6	$189.56	8.370%	$205.4262	$205.43	$205.45	$205.40
Purchase #7	$100.56	9.523%	$110.1363	$110.14	$110.15	$110.10
7 purchase totals =	$913.72		$1,002.4600	$1,002.47	$1,002.50	$1,002.40