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	$32.88	8.375%	$35.6337	$35.63	$35.65	$35.60
Purchase #2	$192.29	3.470%	$198.9625	$198.96	$198.95	$199.00
Purchase #3	$34.82	3.283%	$35.9631	$35.96	$35.95	$36.00
Purchase #4	$63.91	5.660%	$67.5273	$67.53	$67.55	$67.50
Purchase #5	$39.79	7.767%	$42.8805	$42.88	$42.90	$42.90
Purchase #6	$194.88	11.614%	$217.5134	$217.51	$217.50	$217.50
Purchase #7	$12.77	13.596%	$14.5062	$14.51	$14.50	$14.50
7 purchase totals =	$571.34		$612.9867	$612.98	$613.00	$613.00