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	$62.47	7.699%	$67.2796	$67.28	$67.30	$67.30
Purchase #2	$208.56	3.626%	$216.1224	$216.12	$216.10	$216.10
Purchase #3	$53.32	11.796%	$59.6096	$59.61	$59.60	$59.60
Purchase #4	$237.82	9.237%	$259.7874	$259.79	$259.80	$259.80
Purchase #5	$236.89	7.823%	$255.4219	$255.42	$255.40	$255.40
Purchase #6	$250.60	13.402%	$284.1854	$284.19	$284.20	$284.20
Purchase #7	$233.34	12.372%	$262.2088	$262.21	$262.20	$262.20
7 purchase totals =	$1,283.00		$1,404.6151	$1,404.62	$1,404.60	$1,404.60