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	$90.59	4.845%	$94.9791	$94.98	$95.00	$95.00
Purchase #2	$116.77	9.525%	$127.8923	$127.89	$127.90	$127.90
Purchase #3	$31.80	3.132%	$32.796	$32.80	$32.80	$32.80
Purchase #4	$187.66	10.281%	$206.9533	$206.95	$206.95	$207.00
Purchase #5	$212.45	7.826%	$229.0763	$229.08	$229.10	$229.10
Purchase #6	$80.89	11.617%	$90.287	$90.29	$90.30	$90.30
Purchase #7	$79.37	8.842%	$86.3879	$86.39	$86.40	$86.40
7 purchase totals =	$799.53		$868.3719	$868.38	$868.45	$868.50