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	$214.78	5.196%	$225.94	$225.94	$225.95	$225.90
Purchase #2	$216.68	3.816%	$224.9485	$224.95	$224.95	$224.90
Purchase #3	$141.89	9.276%	$155.0517	$155.05	$155.05	$155.10
Purchase #4	$149.80	12.294%	$168.2164	$168.22	$168.20	$168.20
Purchase #5	$131.94	13.781%	$150.1227	$150.12	$150.10	$150.10
Purchase #6	$52.44	10.335%	$57.8597	$57.86	$57.85	$57.90
Purchase #7	$116.33	8.445%	$126.1541	$126.15	$126.15	$126.20
7 purchase totals =	$1,023.86		$1,108.2931	$1,108.29	$1,108.25	$1,108.30