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	$248.76	5.458%	$262.3373	$262.34	$262.35	$262.30
Purchase #2	$143.89	4.844%	$150.86	$150.86	$150.85	$150.90
Purchase #3	$53.95	5.601%	$56.9717	$56.97	$56.95	$57.00
Purchase #4	$225.94	10.866%	$250.4906	$250.49	$250.50	$250.50
Purchase #5	$90.86	8.382%	$98.4759	$98.48	$98.50	$98.50
Purchase #6	$54.72	8.429%	$59.3323	$59.33	$59.35	$59.30
Purchase #7	$148.83	13.629%	$169.114	$169.11	$169.10	$169.10
7 purchase totals =	$966.95		$1,047.5818	$1,047.58	$1,047.60	$1,047.60