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	$204.99	7.274%	$219.901	$219.90	$219.90	$219.90
Purchase #2	$40.88	10.219%	$45.0575	$45.06	$45.05	$45.10
Purchase #3	$124.80	9.313%	$136.4226	$136.42	$136.40	$136.40
Purchase #4	$69.80	5.427%	$73.588	$73.59	$73.60	$73.60
Purchase #5	$144.51	4.445%	$150.9335	$150.93	$150.95	$150.90
Purchase #6	$220.41	11.824%	$246.4713	$246.47	$246.45	$246.50
Purchase #7	$167.88	12.347%	$188.6081	$188.61	$188.60	$188.60
7 purchase totals =	$973.27		$1,060.9820	$1,060.98	$1,060.95	$1,061.00