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	$214.85	4.778%	$225.1155	$225.12	$225.10	$225.10
Purchase #2	$169.26	4.275%	$176.4959	$176.50	$176.50	$176.50
Purchase #3	$136.40	10.168%	$150.2692	$150.27	$150.25	$150.30
Purchase #4	$53.71	10.320%	$59.2529	$59.25	$59.25	$59.30
Purchase #5	$209.41	10.196%	$230.7614	$230.76	$230.75	$230.80
Purchase #6	$29.80	8.629%	$32.3714	$32.37	$32.35	$32.40
Purchase #7	$123.89	3.181%	$127.8309	$127.83	$127.85	$127.80
7 purchase totals =	$937.32		$1,002.0972	$1,002.10	$1,002.05	$1,002.20