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	$60.34	3.195%	$62.2679	$62.27	$62.25	$62.30
Purchase #2	$33.37	5.572%	$35.2294	$35.23	$35.25	$35.20
Purchase #3	$72.83	8.144%	$78.7613	$78.76	$78.75	$78.80
Purchase #4	$209.34	3.358%	$216.3696	$216.37	$216.35	$216.40
Purchase #5	$58.85	6.114%	$62.4481	$62.45	$62.45	$62.40
Purchase #6	$206.74	8.249%	$223.794	$223.79	$223.80	$223.80
Purchase #7	$183.52	4.768%	$192.2702	$192.27	$192.25	$192.30
7 purchase totals =	$824.99		$871.1405	$871.14	$871.10	$871.20