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	$218.96	7.784%	$236.0038	$236.00	$236.00	$236.00
Purchase #2	$44.39	4.701%	$46.4768	$46.48	$46.50	$46.50
Purchase #3	$151.78	11.818%	$169.7174	$169.72	$169.70	$169.70
Purchase #4	$246.29	6.619%	$262.5919	$262.59	$262.60	$262.60
Purchase #5	$151.68	10.843%	$168.1267	$168.13	$168.15	$168.10
Purchase #6	$45.85	13.201%	$51.9027	$51.90	$51.90	$51.90
Purchase #7	$155.92	4.107%	$162.3236	$162.32	$162.30	$162.30
7 purchase totals =	$1,014.87		$1,097.1429	$1,097.14	$1,097.15	$1,097.10