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	$245.69	8.792%	$267.2911	$267.29	$267.30	$267.30
Purchase #2	$175.71	6.856%	$187.7567	$187.76	$187.75	$187.80
Purchase #3	$47.36	5.196%	$49.8208	$49.82	$49.80	$49.80
Purchase #4	$172.28	4.591%	$180.1894	$180.19	$180.20	$180.20
Purchase #5	$63.60	6.796%	$67.9223	$67.92	$67.90	$67.90
Purchase #6	$182.83	7.462%	$196.4728	$196.47	$196.45	$196.50
Purchase #7	$224.85	9.699%	$246.6582	$246.66	$246.65	$246.70
7 purchase totals =	$1,112.32		$1,196.1113	$1,196.11	$1,196.05	$1,196.20