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	$103.56	7.172%	$110.9873	$110.99	$111.00	$111.00
Purchase #2	$179.94	5.637%	$190.0832	$190.08	$190.10	$190.10
Purchase #3	$194.47	11.499%	$216.8321	$216.83	$216.85	$216.80
Purchase #4	$173.89	7.673%	$187.2326	$187.23	$187.25	$187.20
Purchase #5	$59.97	4.338%	$62.5715	$62.57	$62.55	$62.60
Purchase #6	$89.55	12.445%	$100.6945	$100.69	$100.70	$100.70
Purchase #7	$213.92	9.238%	$233.6819	$233.68	$233.70	$233.70
7 purchase totals =	$1,015.30		$1,102.0831	$1,102.07	$1,102.15	$1,102.10