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	$71.35	6.606%	$76.0634	$76.06	$76.05	$76.10
Purchase #2	$236.58	4.765%	$247.853	$247.85	$247.85	$247.90
Purchase #3	$79.61	4.815%	$83.4432	$83.44	$83.45	$83.40
Purchase #4	$104.55	11.546%	$116.6213	$116.62	$116.60	$116.60
Purchase #5	$245.78	11.182%	$273.2631	$273.26	$273.25	$273.30
Purchase #6	$134.79	10.333%	$148.7179	$148.72	$148.70	$148.70
Purchase #7	$124.60	5.337%	$131.2499	$131.25	$131.25	$131.20
7 purchase totals =	$997.26		$1,077.2118	$1,077.20	$1,077.15	$1,077.20