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	$95.81	11.127%	$106.4708	$106.47	$106.45	$106.50
Purchase #2	$12.97	11.648%	$14.4807	$14.48	$14.50	$14.50
Purchase #3	$67.98	6.349%	$72.2961	$72.30	$72.30	$72.30
Purchase #4	$207.36	11.218%	$230.6216	$230.62	$230.60	$230.60
Purchase #5	$182.93	7.452%	$196.5619	$196.56	$196.55	$196.60
Purchase #6	$68.82	7.489%	$73.9739	$73.97	$73.95	$74.00
Purchase #7	$89.82	13.458%	$101.908	$101.91	$101.90	$101.90
7 purchase totals =	$725.69		$796.3130	$796.31	$796.25	$796.40