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	$145.28	4.570%	$151.9193	$151.92	$151.90	$151.90
Purchase #2	$105.88	12.548%	$119.1658	$119.17	$119.15	$119.20
Purchase #3	$18.46	11.637%	$20.6082	$20.61	$20.60	$20.60
Purchase #4	$39.75	12.581%	$44.7509	$44.75	$44.75	$44.80
Purchase #5	$130.48	4.631%	$136.5225	$136.52	$136.50	$136.50
Purchase #6	$222.67	10.665%	$246.4178	$246.42	$246.40	$246.40
Purchase #7	$203.31	11.140%	$225.9587	$225.96	$225.95	$226.00
7 purchase totals =	$865.83		$945.3432	$945.35	$945.25	$945.40