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	$140.92	9.605%	$154.4554	$154.46	$154.45	$154.50
Purchase #2	$81.29	9.526%	$89.0337	$89.03	$89.05	$89.00
Purchase #3	$50.65	9.698%	$55.562	$55.56	$55.55	$55.60
Purchase #4	$43.64	7.199%	$46.7816	$46.78	$46.80	$46.80
Purchase #5	$225.97	11.279%	$251.4572	$251.46	$251.45	$251.50
Purchase #6	$200.86	13.689%	$228.3557	$228.36	$228.35	$228.40
Purchase #7	$190.61	7.502%	$204.9096	$204.91	$204.90	$204.90
7 purchase totals =	$933.94		$1,030.5552	$1,030.56	$1,030.55	$1,030.70