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	$10.38	5.386%	$10.9391	$10.94	$10.95	$10.90
Purchase #2	$231.53	4.766%	$242.5647	$242.56	$242.55	$242.60
Purchase #3	$126.97	10.199%	$139.9197	$139.92	$139.90	$139.90
Purchase #4	$146.33	3.411%	$151.3213	$151.32	$151.30	$151.30
Purchase #5	$182.92	8.763%	$198.9493	$198.95	$198.95	$198.90
Purchase #6	$14.34	10.593%	$15.859	$15.86	$15.85	$15.90
Purchase #7	$228.86	11.503%	$255.1858	$255.19	$255.20	$255.20
7 purchase totals =	$941.33		$1,014.7389	$1,014.74	$1,014.70	$1,014.70