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	$214.62	10.504%	$237.1637	$237.16	$237.15	$237.20
Purchase #2	$123.78	10.327%	$136.5628	$136.56	$136.55	$136.60
Purchase #3	$93.77	7.279%	$100.5955	$100.60	$100.60	$100.60
Purchase #4	$81.70	12.264%	$91.7197	$91.72	$91.70	$91.70
Purchase #5	$138.40	5.631%	$146.1933	$146.19	$146.20	$146.20
Purchase #6	$32.33	3.477%	$33.4541	$33.45	$33.45	$33.50
Purchase #7	$12.79	3.745%	$13.269	$13.27	$13.25	$13.30
7 purchase totals =	$697.39		$758.9581	$758.95	$758.90	$759.10