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	$95.59	9.841%	$104.997	$105.00	$105.00	$105.00
Purchase #2	$215.25	10.825%	$238.5508	$238.55	$238.55	$238.60
Purchase #3	$216.76	3.807%	$225.0121	$225.01	$225.00	$225.00
Purchase #4	$163.43	11.421%	$182.0953	$182.10	$182.10	$182.10
Purchase #5	$152.78	4.286%	$159.3282	$159.33	$159.35	$159.30
Purchase #6	$234.51	13.683%	$266.598	$266.60	$266.60	$266.60
Purchase #7	$43.54	8.668%	$47.314	$47.31	$47.30	$47.30
7 purchase totals =	$1,121.86		$1,223.8954	$1,223.90	$1,223.90	$1,223.90