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	$196.27	6.606%	$209.2356	$209.24	$209.25	$209.20
Purchase #2	$207.39	4.796%	$217.3364	$217.34	$217.35	$217.30
Purchase #3	$54.49	12.451%	$61.2745	$61.27	$61.25	$61.30
Purchase #4	$44.27	4.732%	$46.3649	$46.36	$46.35	$46.40
Purchase #5	$230.39	10.366%	$254.2722	$254.27	$254.25	$254.30
Purchase #6	$72.88	13.820%	$82.952	$82.95	$82.95	$83.00
Purchase #7	$141.65	4.649%	$148.2353	$148.24	$148.25	$148.20
7 purchase totals =	$947.34		$1,019.6709	$1,019.67	$1,019.65	$1,019.70