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	$110.27	3.548%	$114.1824	$114.18	$114.20	$114.20
Purchase #2	$70.58	6.257%	$74.9962	$75.00	$75.00	$75.00
Purchase #3	$14.60	6.320%	$15.5227	$15.52	$15.50	$15.50
Purchase #4	$226.78	3.443%	$234.588	$234.59	$234.60	$234.60
Purchase #5	$224.47	13.826%	$255.5052	$255.51	$255.50	$255.50
Purchase #6	$140.50	10.702%	$155.5363	$155.54	$155.55	$155.50
Purchase #7	$38.66	11.567%	$43.1318	$43.13	$43.15	$43.10
7 purchase totals =	$825.86		$893.4626	$893.47	$893.50	$893.40