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	$181.61	11.213%	$201.9739	$201.97	$201.95	$202.00
Purchase #2	$101.62	13.514%	$115.3529	$115.35	$115.35	$115.40
Purchase #3	$241.56	9.338%	$264.1169	$264.12	$264.10	$264.10
Purchase #4	$50.94	11.520%	$56.8083	$56.81	$56.80	$56.80
Purchase #5	$245.48	4.617%	$256.8138	$256.81	$256.80	$256.80
Purchase #6	$112.55	10.274%	$124.1134	$124.11	$124.10	$124.10
Purchase #7	$37.55	12.469%	$42.2321	$42.23	$42.25	$42.20
7 purchase totals =	$971.31		$1,061.4113	$1,061.40	$1,061.35	$1,061.40