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	$153.66	5.716%	$162.4432	$162.44	$162.45	$162.40
Purchase #2	$134.82	12.399%	$151.5363	$151.54	$151.55	$151.50
Purchase #3	$133.36	9.820%	$146.456	$146.46	$146.45	$146.50
Purchase #4	$247.65	7.351%	$265.8548	$265.85	$265.85	$265.90
Purchase #5	$198.47	5.279%	$208.9472	$208.95	$208.95	$208.90
Purchase #6	$175.41	4.401%	$183.1298	$183.13	$183.15	$183.10
Purchase #7	$75.77	3.291%	$78.2636	$78.26	$78.25	$78.30
7 purchase totals =	$1,119.14		$1,196.6309	$1,196.63	$1,196.65	$1,196.60