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	$110.60	3.249%	$114.1934	$114.19	$114.20	$114.20
Purchase #2	$187.37	4.617%	$196.0209	$196.02	$196.00	$196.00
Purchase #3	$231.86	4.163%	$241.5123	$241.51	$241.50	$241.50
Purchase #4	$82.73	3.472%	$85.6024	$85.60	$85.60	$85.60
Purchase #5	$219.37	6.348%	$233.2956	$233.30	$233.30	$233.30
Purchase #6	$35.70	9.617%	$39.1333	$39.13	$39.15	$39.10
Purchase #7	$166.52	10.139%	$183.4035	$183.40	$183.40	$183.40
7 purchase totals =	$1,034.15		$1,093.1614	$1,093.15	$1,093.15	$1,093.10