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	$196.47	4.779%	$205.8593	$205.86	$205.85	$205.90
Purchase #2	$40.91	11.141%	$45.4678	$45.47	$45.45	$45.50
Purchase #3	$135.63	7.856%	$146.2851	$146.29	$146.30	$146.30
Purchase #4	$243.27	13.511%	$276.1382	$276.14	$276.15	$276.10
Purchase #5	$131.87	8.356%	$142.8891	$142.89	$142.90	$142.90
Purchase #6	$172.67	5.800%	$182.6849	$182.68	$182.70	$182.70
Purchase #7	$43.29	8.637%	$47.029	$47.03	$47.05	$47.00
7 purchase totals =	$964.11		$1,046.3534	$1,046.36	$1,046.40	$1,046.40