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	$124.54	6.436%	$132.5554	$132.56	$132.55	$132.60
Purchase #2	$141.34	5.649%	$149.3243	$149.32	$149.30	$149.30
Purchase #3	$167.72	5.230%	$176.4918	$176.49	$176.50	$176.50
Purchase #4	$199.81	11.554%	$222.896	$222.90	$222.90	$222.90
Purchase #5	$232.50	10.104%	$255.9918	$255.99	$256.00	$256.00
Purchase #6	$25.73	7.125%	$27.5633	$27.56	$27.55	$27.60
Purchase #7	$91.95	5.404%	$96.919	$96.92	$96.90	$96.90
7 purchase totals =	$983.59		$1,061.7416	$1,061.74	$1,061.70	$1,061.80