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	$229.77	6.751%	$245.2818	$245.28	$245.30	$245.30
Purchase #2	$222.98	6.731%	$237.9888	$237.99	$238.00	$238.00
Purchase #3	$68.61	3.670%	$71.128	$71.13	$71.15	$71.10
Purchase #4	$217.67	9.564%	$238.488	$238.49	$238.50	$238.50
Purchase #5	$192.95	12.641%	$217.3408	$217.34	$217.35	$217.30
Purchase #6	$249.69	12.456%	$280.7914	$280.79	$280.80	$280.80
Purchase #7	$99.67	10.269%	$109.9051	$109.91	$109.90	$109.90
7 purchase totals =	$1,281.34		$1,400.9239	$1,400.93	$1,401.00	$1,400.90