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	$63.92	12.545%	$71.9388	$71.94	$71.95	$71.90
Purchase #2	$10.52	11.452%	$11.7248	$11.72	$11.70	$11.70
Purchase #3	$235.69	12.171%	$264.3758	$264.38	$264.40	$264.40
Purchase #4	$194.41	7.844%	$209.6595	$209.66	$209.65	$209.70
Purchase #5	$167.76	11.742%	$187.4584	$187.46	$187.45	$187.50
Purchase #6	$248.96	12.615%	$280.3663	$280.37	$280.35	$280.40
Purchase #7	$88.39	12.143%	$99.1232	$99.12	$99.10	$99.10
7 purchase totals =	$1,009.65		$1,124.6468	$1,124.65	$1,124.60	$1,124.70