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	$219.95	9.823%	$241.5557	$241.56	$241.55	$241.60
Purchase #2	$197.94	4.189%	$206.2317	$206.23	$206.25	$206.20
Purchase #3	$15.60	9.645%	$17.1046	$17.10	$17.10	$17.10
Purchase #4	$208.33	13.793%	$237.065	$237.07	$237.05	$237.10
Purchase #5	$80.62	12.753%	$90.9015	$90.90	$90.90	$90.90
Purchase #6	$99.26	10.301%	$109.4848	$109.48	$109.50	$109.50
Purchase #7	$136.76	10.582%	$151.2319	$151.23	$151.25	$151.20
7 purchase totals =	$958.46		$1,053.5752	$1,053.57	$1,053.60	$1,053.60