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	$44.27	8.359%	$47.9705	$47.97	$47.95	$48.00
Purchase #2	$14.56	4.207%	$15.1725	$15.17	$15.15	$15.20
Purchase #3	$167.78	8.536%	$182.1017	$182.10	$182.10	$182.10
Purchase #4	$100.52	11.352%	$111.931	$111.93	$111.95	$111.90
Purchase #5	$45.89	5.416%	$48.3754	$48.38	$48.40	$48.40
Purchase #6	$160.61	3.190%	$165.7335	$165.73	$165.75	$165.70
Purchase #7	$234.28	7.112%	$250.942	$250.94	$250.95	$250.90
7 purchase totals =	$767.91		$822.2266	$822.22	$822.25	$822.20