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	$100.63	6.273%	$106.9425	$106.94	$106.95	$106.90
Purchase #2	$123.53	6.244%	$131.2432	$131.24	$131.25	$131.20
Purchase #3	$37.88	5.494%	$39.9611	$39.96	$39.95	$40.00
Purchase #4	$87.90	5.603%	$92.825	$92.83	$92.85	$92.80
Purchase #5	$46.98	13.540%	$53.3411	$53.34	$53.35	$53.30
Purchase #6	$235.69	3.631%	$244.2479	$244.25	$244.25	$244.20
Purchase #7	$39.84	6.697%	$42.5081	$42.51	$42.50	$42.50
7 purchase totals =	$672.45		$711.0689	$711.07	$711.10	$710.90