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	$12.89	11.303%	$14.347	$14.35	$14.35	$14.30
Purchase #2	$82.90	8.298%	$89.779	$89.78	$89.80	$89.80
Purchase #3	$78.95	13.431%	$89.5538	$89.55	$89.55	$89.60
Purchase #4	$215.86	3.602%	$223.6353	$223.64	$223.65	$223.60
Purchase #5	$146.52	4.682%	$153.3801	$153.38	$153.40	$153.40
Purchase #6	$210.99	8.812%	$229.5824	$229.58	$229.60	$229.60
Purchase #7	$213.36	11.266%	$237.3971	$237.40	$237.40	$237.40
7 purchase totals =	$961.47		$1,037.6747	$1,037.68	$1,037.75	$1,037.70