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	$182.64	8.195%	$197.6073	$197.61	$197.60	$197.60
Purchase #2	$11.39	4.766%	$11.9328	$11.93	$11.95	$11.90
Purchase #3	$25.29	6.862%	$27.0254	$27.03	$27.05	$27.00
Purchase #4	$37.48	12.457%	$42.1489	$42.15	$42.15	$42.10
Purchase #5	$131.94	7.463%	$141.7867	$141.79	$141.80	$141.80
Purchase #6	$232.79	3.344%	$240.5745	$240.57	$240.55	$240.60
Purchase #7	$109.85	13.347%	$124.5117	$124.51	$124.50	$124.50
7 purchase totals =	$731.38		$785.5873	$785.59	$785.60	$785.50