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	$208.31	6.809%	$222.4938	$222.49	$222.50	$222.50
Purchase #2	$188.40	4.358%	$196.6105	$196.61	$196.60	$196.60
Purchase #3	$214.50	11.306%	$238.7514	$238.75	$238.75	$238.80
Purchase #4	$85.40	8.219%	$92.419	$92.42	$92.40	$92.40
Purchase #5	$54.74	5.148%	$57.558	$57.56	$57.55	$57.60
Purchase #6	$13.57	6.810%	$14.4941	$14.49	$14.50	$14.50
Purchase #7	$169.44	8.870%	$184.4693	$184.47	$184.45	$184.50
7 purchase totals =	$934.36		$1,006.7961	$1,006.79	$1,006.75	$1,006.90