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	$189.28	13.570%	$214.9653	$214.97	$214.95	$215.00
Purchase #2	$90.71	10.733%	$100.4459	$100.45	$100.45	$100.40
Purchase #3	$205.42	7.310%	$220.4362	$220.44	$220.45	$220.40
Purchase #4	$78.79	10.241%	$86.8589	$86.86	$86.85	$86.90
Purchase #5	$152.27	13.154%	$172.2996	$172.30	$172.30	$172.30
Purchase #6	$74.40	12.175%	$83.4582	$83.46	$83.45	$83.50
Purchase #7	$173.49	12.543%	$195.2509	$195.25	$195.25	$195.30
7 purchase totals =	$964.36		$1,073.7150	$1,073.73	$1,073.70	$1,073.80