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	$124.95	13.501%	$141.8195	$141.82	$141.80	$141.80
Purchase #2	$36.29	3.779%	$37.6614	$37.66	$37.65	$37.70
Purchase #3	$182.65	13.339%	$207.0137	$207.01	$207.00	$207.00
Purchase #4	$171.78	7.661%	$184.9401	$184.94	$184.95	$184.90
Purchase #5	$142.47	7.549%	$153.2251	$153.23	$153.25	$153.20
Purchase #6	$207.69	11.460%	$231.4913	$231.49	$231.50	$231.50
Purchase #7	$158.39	6.397%	$168.5222	$168.52	$168.50	$168.50
7 purchase totals =	$1,024.22		$1,124.6733	$1,124.67	$1,124.65	$1,124.60