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	$87.72	4.837%	$91.963	$91.96	$91.95	$92.00
Purchase #2	$168.81	3.510%	$174.7352	$174.74	$174.75	$174.70
Purchase #3	$197.53	12.864%	$222.9403	$222.94	$222.95	$222.90
Purchase #4	$115.33	11.803%	$128.9424	$128.94	$128.95	$128.90
Purchase #5	$221.36	4.638%	$231.6267	$231.63	$231.65	$231.60
Purchase #6	$78.74	13.792%	$89.5998	$89.60	$89.60	$89.60
Purchase #7	$87.61	3.274%	$90.4784	$90.48	$90.50	$90.50
7 purchase totals =	$957.10		$1,030.2858	$1,030.29	$1,030.35	$1,030.20