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	$86.82	6.124%	$92.1369	$92.14	$92.15	$92.10
Purchase #2	$90.75	13.521%	$103.0203	$103.02	$103.00	$103.00
Purchase #3	$159.83	8.678%	$173.7	$173.70	$173.70	$173.70
Purchase #4	$188.64	10.475%	$208.4	$208.40	$208.40	$208.40
Purchase #5	$63.59	12.697%	$71.664	$71.66	$71.65	$71.70
Purchase #6	$142.56	4.378%	$148.8013	$148.80	$148.80	$148.80
Purchase #7	$196.67	8.380%	$213.1509	$213.15	$213.15	$213.20
7 purchase totals =	$928.86		$1,010.8734	$1,010.87	$1,010.85	$1,010.90