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	$97.68	11.543%	$108.9552	$108.96	$108.95	$109.00
Purchase #2	$37.53	6.103%	$39.8205	$39.82	$39.80	$39.80
Purchase #3	$120.95	5.119%	$127.1414	$127.14	$127.15	$127.10
Purchase #4	$216.66	5.831%	$229.2934	$229.29	$229.30	$229.30
Purchase #5	$124.70	4.683%	$130.5397	$130.54	$130.55	$130.50
Purchase #6	$247.63	13.851%	$281.9292	$281.93	$281.95	$281.90
Purchase #7	$87.30	13.314%	$98.9231	$98.92	$98.90	$98.90
7 purchase totals =	$932.45		$1,016.6025	$1,016.60	$1,016.60	$1,016.50