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	$71.41	3.164%	$73.6694	$73.67	$73.65	$73.70
Purchase #2	$67.98	6.399%	$72.33	$72.33	$72.35	$72.30
Purchase #3	$139.55	6.479%	$148.5914	$148.59	$148.60	$148.60
Purchase #4	$246.71	3.602%	$255.5965	$255.60	$255.60	$255.60
Purchase #5	$199.26	8.806%	$216.8068	$216.81	$216.80	$216.80
Purchase #6	$41.84	6.775%	$44.6747	$44.67	$44.65	$44.70
Purchase #7	$45.55	13.683%	$51.7826	$51.78	$51.80	$51.80
7 purchase totals =	$812.30		$863.4514	$863.45	$863.45	$863.50