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	$161.52	4.833%	$169.3263	$169.33	$169.35	$169.30
Purchase #2	$38.82	4.553%	$40.5875	$40.59	$40.60	$40.60
Purchase #3	$33.75	13.712%	$38.3778	$38.38	$38.40	$38.40
Purchase #4	$159.45	7.799%	$171.8855	$171.89	$171.90	$171.90
Purchase #5	$5.85	11.352%	$6.5141	$6.51	$6.50	$6.50
Purchase #6	$211.56	4.428%	$220.9279	$220.93	$220.95	$220.90
Purchase #7	$120.95	3.790%	$125.534	$125.53	$125.55	$125.50
7 purchase totals =	$731.90		$773.1531	$773.16	$773.25	$773.10