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	$152.60	6.770%	$162.931	$162.93	$162.95	$162.90
Purchase #2	$102.50	13.471%	$116.3078	$116.31	$116.30	$116.30
Purchase #3	$109.56	12.423%	$123.1706	$123.17	$123.15	$123.20
Purchase #4	$14.98	9.495%	$16.4024	$16.40	$16.40	$16.40
Purchase #5	$225.48	8.176%	$243.9152	$243.92	$243.90	$243.90
Purchase #6	$196.90	11.433%	$219.4116	$219.41	$219.40	$219.40
Purchase #7	$123.25	6.794%	$131.6236	$131.62	$131.60	$131.60
7 purchase totals =	$925.27		$1,013.7622	$1,013.76	$1,013.70	$1,013.70