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	$176.55	11.451%	$196.7667	$196.77	$196.75	$196.80
Purchase #2	$77.34	7.783%	$83.3594	$83.36	$83.35	$83.40
Purchase #3	$192.44	11.863%	$215.2692	$215.27	$215.25	$215.30
Purchase #4	$142.53	13.677%	$162.0238	$162.02	$162.00	$162.00
Purchase #5	$31.70	6.516%	$33.7656	$33.77	$33.75	$33.80
Purchase #6	$172.63	10.399%	$190.5818	$190.58	$190.60	$190.60
Purchase #7	$238.73	11.657%	$266.5588	$266.56	$266.55	$266.60
7 purchase totals =	$1,031.92		$1,148.3253	$1,148.33	$1,148.25	$1,148.50