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	$214.75	9.407%	$234.9515	$234.95	$234.95	$235.00
Purchase #2	$144.56	4.781%	$151.4714	$151.47	$151.45	$151.50
Purchase #3	$170.90	5.696%	$180.6345	$180.63	$180.65	$180.60
Purchase #4	$52.41	10.257%	$57.7857	$57.79	$57.80	$57.80
Purchase #5	$45.33	9.109%	$49.4591	$49.46	$49.45	$49.50
Purchase #6	$165.85	5.614%	$175.1608	$175.16	$175.15	$175.20
Purchase #7	$165.73	9.448%	$181.3882	$181.39	$181.40	$181.40
7 purchase totals =	$959.53		$1,030.8512	$1,030.85	$1,030.85	$1,031.00