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	$72.67	4.638%	$76.0404	$76.04	$76.05	$76.00
Purchase #2	$235.34	13.504%	$267.1203	$267.12	$267.10	$267.10
Purchase #3	$96.34	10.566%	$106.5193	$106.52	$106.50	$106.50
Purchase #4	$232.72	11.441%	$259.3455	$259.35	$259.35	$259.30
Purchase #5	$151.37	5.656%	$159.9315	$159.93	$159.95	$159.90
Purchase #6	$18.39	5.439%	$19.3902	$19.39	$19.40	$19.40
Purchase #7	$115.39	10.698%	$127.7344	$127.73	$127.75	$127.70
7 purchase totals =	$922.22		$1,016.0816	$1,016.08	$1,016.10	$1,015.90