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	$210.72	4.177%	$219.5218	$219.52	$219.50	$219.50
Purchase #2	$195.95	4.496%	$204.7599	$204.76	$204.75	$204.80
Purchase #3	$9.45	12.142%	$10.5974	$10.60	$10.60	$10.60
Purchase #4	$191.26	6.393%	$203.4873	$203.49	$203.50	$203.50
Purchase #5	$157.57	13.655%	$179.0862	$179.09	$179.10	$179.10
Purchase #6	$153.91	9.381%	$168.3483	$168.35	$168.35	$168.30
Purchase #7	$155.97	5.428%	$164.4361	$164.44	$164.45	$164.40
7 purchase totals =	$1,074.83		$1,150.2370	$1,150.25	$1,150.25	$1,150.20