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	$162.81	9.611%	$178.4577	$178.46	$178.45	$178.50
Purchase #2	$116.75	9.105%	$127.3801	$127.38	$127.40	$127.40
Purchase #3	$75.31	10.695%	$83.3644	$83.36	$83.35	$83.40
Purchase #4	$30.66	3.463%	$31.7218	$31.72	$31.70	$31.70
Purchase #5	$199.99	7.869%	$215.7272	$215.73	$215.75	$215.70
Purchase #6	$206.81	7.492%	$222.3042	$222.30	$222.30	$222.30
Purchase #7	$227.89	8.649%	$247.6002	$247.60	$247.60	$247.60
7 purchase totals =	$1,020.22		$1,106.5556	$1,106.55	$1,106.55	$1,106.60