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	$68.42	4.689%	$71.6282	$71.63	$71.65	$71.60
Purchase #2	$15.31	4.861%	$16.0542	$16.05	$16.05	$16.10
Purchase #3	$60.27	11.720%	$67.3336	$67.33	$67.35	$67.30
Purchase #4	$62.31	12.119%	$69.8613	$69.86	$69.85	$69.90
Purchase #5	$115.36	7.201%	$123.6671	$123.67	$123.65	$123.70
Purchase #6	$49.79	12.342%	$55.9351	$55.94	$55.95	$55.90
Purchase #7	$157.47	7.228%	$168.8519	$168.85	$168.85	$168.90
7 purchase totals =	$528.93		$573.3314	$573.33	$573.35	$573.40