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	$86.46	11.480%	$96.3856	$96.39	$96.40	$96.40
Purchase #2	$36.56	3.737%	$37.9262	$37.93	$37.95	$37.90
Purchase #3	$208.77	7.303%	$224.0165	$224.02	$224.00	$224.00
Purchase #4	$167.66	13.785%	$190.7719	$190.77	$190.75	$190.80
Purchase #5	$155.78	4.561%	$162.8851	$162.89	$162.90	$162.90
Purchase #6	$190.79	11.410%	$212.5591	$212.56	$212.55	$212.60
Purchase #7	$12.72	5.315%	$13.3961	$13.40	$13.40	$13.40
7 purchase totals =	$858.74		$937.9405	$937.96	$937.95	$938.00