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	$211.75	11.125%	$235.3072	$235.31	$235.30	$235.30
Purchase #2	$41.56	11.338%	$46.2721	$46.27	$46.25	$46.30
Purchase #3	$38.29	5.769%	$40.499	$40.50	$40.50	$40.50
Purchase #4	$98.27	11.733%	$109.8	$109.80	$109.80	$109.80
Purchase #5	$145.48	5.328%	$153.2312	$153.23	$153.25	$153.20
Purchase #6	$148.25	13.663%	$168.5054	$168.51	$168.50	$168.50
Purchase #7	$47.73	13.132%	$53.9979	$54.00	$54.00	$54.00
7 purchase totals =	$731.33		$807.6128	$807.62	$807.60	$807.60