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	$212.33	6.725%	$226.6092	$226.61	$226.60	$226.60
Purchase #2	$219.56	10.615%	$242.8663	$242.87	$242.85	$242.90
Purchase #3	$29.79	3.129%	$30.7221	$30.72	$30.70	$30.70
Purchase #4	$113.85	10.686%	$126.016	$126.02	$126.00	$126.00
Purchase #5	$238.66	9.150%	$260.4974	$260.50	$260.50	$260.50
Purchase #6	$56.79	4.554%	$59.3762	$59.38	$59.40	$59.40
Purchase #7	$96.88	3.816%	$100.5769	$100.58	$100.60	$100.60
7 purchase totals =	$967.86		$1,046.6641	$1,046.68	$1,046.65	$1,046.70