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	$105.35	6.464%	$112.1598	$112.16	$112.15	$112.20
Purchase #2	$215.81	13.758%	$245.5011	$245.50	$245.50	$245.50
Purchase #3	$148.34	5.382%	$156.3237	$156.32	$156.30	$156.30
Purchase #4	$43.98	12.183%	$49.3381	$49.34	$49.35	$49.30
Purchase #5	$211.71	4.264%	$220.7373	$220.74	$220.75	$220.70
Purchase #6	$83.57	11.122%	$92.8647	$92.86	$92.85	$92.90
Purchase #7	$53.73	3.221%	$55.4606	$55.46	$55.45	$55.50
7 purchase totals =	$862.49		$932.3853	$932.38	$932.35	$932.40