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	$100.89	13.375%	$114.384	$114.38	$114.40	$114.40
Purchase #2	$82.89	10.190%	$91.3365	$91.34	$91.35	$91.30
Purchase #3	$126.58	11.874%	$141.6101	$141.61	$141.60	$141.60
Purchase #4	$185.28	10.824%	$205.3347	$205.33	$205.35	$205.30
Purchase #5	$200.99	11.618%	$224.341	$224.34	$224.35	$224.30
Purchase #6	$173.75	7.412%	$186.6284	$186.63	$186.65	$186.60
Purchase #7	$45.37	3.567%	$46.9883	$46.99	$47.00	$47.00
7 purchase totals =	$915.75		$1,010.6230	$1,010.62	$1,010.70	$1,010.50