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	$185.86	13.725%	$211.3693	$211.37	$211.35	$211.40
Purchase #2	$131.76	3.598%	$136.5007	$136.50	$136.50	$136.50
Purchase #3	$78.71	5.472%	$83.017	$83.02	$83.00	$83.00
Purchase #4	$61.74	8.774%	$67.1571	$67.16	$67.15	$67.20
Purchase #5	$169.62	3.534%	$175.6144	$175.61	$175.60	$175.60
Purchase #6	$195.89	13.379%	$222.0981	$222.10	$222.10	$222.10
Purchase #7	$176.87	13.187%	$200.1938	$200.19	$200.20	$200.20
7 purchase totals =	$1,000.45		$1,095.9504	$1,095.95	$1,095.90	$1,096.00