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	$236.82	7.510%	$254.6052	$254.61	$254.60	$254.60
Purchase #2	$14.28	7.761%	$15.3883	$15.39	$15.40	$15.40
Purchase #3	$130.96	8.700%	$142.3535	$142.35	$142.35	$142.40
Purchase #4	$87.33	10.687%	$96.663	$96.66	$96.65	$96.70
Purchase #5	$72.96	5.386%	$76.8896	$76.89	$76.90	$76.90
Purchase #6	$169.86	7.438%	$182.4942	$182.49	$182.50	$182.50
Purchase #7	$138.33	6.607%	$147.4695	$147.47	$147.45	$147.50
7 purchase totals =	$850.54		$915.8633	$915.86	$915.85	$916.00