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	$219.70	3.512%	$227.4159	$227.42	$227.40	$227.40
Purchase #2	$226.37	3.441%	$234.1594	$234.16	$234.15	$234.20
Purchase #3	$232.45	5.796%	$245.9228	$245.92	$245.90	$245.90
Purchase #4	$194.34	12.542%	$218.7141	$218.71	$218.70	$218.70
Purchase #5	$235.54	12.642%	$265.317	$265.32	$265.30	$265.30
Purchase #6	$105.46	3.765%	$109.4306	$109.43	$109.45	$109.40
Purchase #7	$90.81	10.786%	$100.6048	$100.60	$100.60	$100.60
7 purchase totals =	$1,304.67		$1,401.5646	$1,401.56	$1,401.50	$1,401.50