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	$222.71	10.225%	$245.4821	$245.48	$245.50	$245.50
Purchase #2	$151.87	13.309%	$172.0824	$172.08	$172.10	$172.10
Purchase #3	$104.79	10.844%	$116.1534	$116.15	$116.15	$116.20
Purchase #4	$205.76	10.640%	$227.6529	$227.65	$227.65	$227.70
Purchase #5	$167.72	10.536%	$185.391	$185.39	$185.40	$185.40
Purchase #6	$180.76	4.712%	$189.2774	$189.28	$189.30	$189.30
Purchase #7	$182.27	8.473%	$197.7137	$197.71	$197.70	$197.70
7 purchase totals =	$1,215.88		$1,333.7529	$1,333.74	$1,333.80	$1,333.90