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	$194.96	6.235%	$207.1158	$207.12	$207.10	$207.10
Purchase #2	$80.75	9.808%	$88.67	$88.67	$88.65	$88.70
Purchase #3	$42.40	8.239%	$45.8933	$45.89	$45.90	$45.90
Purchase #4	$14.86	6.486%	$15.8238	$15.82	$15.80	$15.80
Purchase #5	$220.86	12.322%	$248.0744	$248.07	$248.05	$248.10
Purchase #6	$168.48	10.108%	$185.51	$185.51	$185.50	$185.50
Purchase #7	$188.67	4.159%	$196.5168	$196.52	$196.50	$196.50
7 purchase totals =	$910.98		$987.6041	$987.60	$987.50	$987.60