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	$60.77	4.549%	$63.5344	$63.53	$63.55	$63.50
Purchase #2	$54.50	12.627%	$61.3817	$61.38	$61.40	$61.40
Purchase #3	$68.33	4.141%	$71.1595	$71.16	$71.15	$71.20
Purchase #4	$76.36	13.718%	$86.8351	$86.84	$86.85	$86.80
Purchase #5	$152.41	10.837%	$168.9267	$168.93	$168.95	$168.90
Purchase #6	$142.27	4.404%	$148.5356	$148.54	$148.55	$148.50
Purchase #7	$105.97	8.199%	$114.6585	$114.66	$114.65	$114.70
7 purchase totals =	$660.61		$715.0315	$715.04	$715.10	$715.00