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	$231.56	7.687%	$249.36	$249.36	$249.35	$249.40
Purchase #2	$50.65	5.854%	$53.6151	$53.62	$53.60	$53.60
Purchase #3	$189.87	4.244%	$197.9281	$197.93	$197.95	$197.90
Purchase #4	$224.90	6.191%	$238.8236	$238.82	$238.80	$238.80
Purchase #5	$172.25	9.575%	$188.7429	$188.74	$188.75	$188.70
Purchase #6	$41.51	7.871%	$44.7773	$44.78	$44.80	$44.80
Purchase #7	$42.37	8.164%	$45.8291	$45.83	$45.85	$45.80
7 purchase totals =	$953.11		$1,019.0761	$1,019.08	$1,019.10	$1,019.00