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	$118.46	9.459%	$129.6651	$129.67	$129.65	$129.70
Purchase #2	$164.94	5.623%	$174.2146	$174.21	$174.20	$174.20
Purchase #3	$179.48	5.435%	$189.2347	$189.23	$189.25	$189.20
Purchase #4	$21.82	7.439%	$23.4432	$23.44	$23.45	$23.40
Purchase #5	$186.38	5.546%	$196.7166	$196.72	$196.70	$196.70
Purchase #6	$123.97	6.133%	$131.5731	$131.57	$131.55	$131.60
Purchase #7	$164.80	6.136%	$174.9121	$174.91	$174.90	$174.90
7 purchase totals =	$959.85		$1,019.7594	$1,019.75	$1,019.70	$1,019.70