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	$223.45	5.566%	$235.8872	$235.89	$235.90	$235.90
Purchase #2	$181.63	3.699%	$188.3485	$188.35	$188.35	$188.30
Purchase #3	$11.76	4.810%	$12.3257	$12.33	$12.35	$12.30
Purchase #4	$207.83	13.193%	$235.249	$235.25	$235.25	$235.20
Purchase #5	$142.85	7.439%	$153.4766	$153.48	$153.50	$153.50
Purchase #6	$237.54	7.734%	$255.9113	$255.91	$255.90	$255.90
Purchase #7	$19.28	3.141%	$19.8856	$19.89	$19.90	$19.90
7 purchase totals =	$1,024.34		$1,101.0839	$1,101.10	$1,101.15	$1,101.00