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	$227.95	7.187%	$244.3328	$244.33	$244.35	$244.30
Purchase #2	$17.37	5.786%	$18.375	$18.38	$18.40	$18.40
Purchase #3	$55.52	13.570%	$63.0541	$63.05	$63.05	$63.10
Purchase #4	$200.49	11.206%	$222.9569	$222.96	$222.95	$223.00
Purchase #5	$246.32	13.423%	$279.3835	$279.38	$279.40	$279.40
Purchase #6	$104.33	11.612%	$116.4448	$116.44	$116.45	$116.40
Purchase #7	$86.80	10.794%	$96.1692	$96.17	$96.15	$96.20
7 purchase totals =	$938.78		$1,040.7163	$1,040.71	$1,040.75	$1,040.80