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	$182.67	7.654%	$196.6516	$196.65	$196.65	$196.70
Purchase #2	$192.40	13.405%	$218.1912	$218.19	$218.20	$218.20
Purchase #3	$33.83	12.443%	$38.0395	$38.04	$38.05	$38.00
Purchase #4	$87.51	13.598%	$99.4096	$99.41	$99.40	$99.40
Purchase #5	$83.86	7.855%	$90.4472	$90.45	$90.45	$90.40
Purchase #6	$160.85	6.214%	$170.8452	$170.85	$170.85	$170.80
Purchase #7	$222.65	11.518%	$248.2948	$248.29	$248.30	$248.30
7 purchase totals =	$963.77		$1,061.8791	$1,061.88	$1,061.90	$1,061.80