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	$89.39	4.514%	$93.4251	$93.43	$93.45	$93.40
Purchase #2	$204.33	4.804%	$214.146	$214.15	$214.15	$214.10
Purchase #3	$101.37	9.864%	$111.3691	$111.37	$111.35	$111.40
Purchase #4	$34.88	7.658%	$37.5511	$37.55	$37.55	$37.60
Purchase #5	$208.76	13.705%	$237.3706	$237.37	$237.35	$237.40
Purchase #6	$121.83	5.771%	$128.8608	$128.86	$128.85	$128.90
Purchase #7	$104.71	13.659%	$119.0123	$119.01	$119.00	$119.00
7 purchase totals =	$865.27		$941.7350	$941.74	$941.70	$941.80