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	$100.74	5.150%	$105.9281	$105.93	$105.95	$105.90
Purchase #2	$237.69	11.262%	$264.4586	$264.46	$264.45	$264.50
Purchase #3	$174.80	11.556%	$194.9999	$195.00	$195.00	$195.00
Purchase #4	$206.54	4.854%	$216.5655	$216.57	$216.55	$216.60
Purchase #5	$232.45	12.650%	$261.8549	$261.85	$261.85	$261.90
Purchase #6	$141.48	10.204%	$155.9166	$155.92	$155.90	$155.90
Purchase #7	$221.83	3.651%	$229.929	$229.93	$229.95	$229.90
7 purchase totals =	$1,315.53		$1,429.6526	$1,429.66	$1,429.65	$1,429.70