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	$225.36	4.712%	$235.979	$235.98	$236.00	$236.00
Purchase #2	$12.79	13.588%	$14.5279	$14.53	$14.55	$14.50
Purchase #3	$33.84	11.131%	$37.6067	$37.61	$37.60	$37.60
Purchase #4	$61.67	9.491%	$67.5231	$67.52	$67.50	$67.50
Purchase #5	$19.34	3.219%	$19.9626	$19.96	$19.95	$20.00
Purchase #6	$195.27	6.759%	$208.4683	$208.47	$208.45	$208.50
Purchase #7	$61.94	6.188%	$65.7728	$65.77	$65.75	$65.80
7 purchase totals =	$610.21		$649.8404	$649.84	$649.80	$649.90