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	$190.38	10.377%	$210.1357	$210.14	$210.15	$210.10
Purchase #2	$11.26	10.794%	$12.4754	$12.48	$12.50	$12.50
Purchase #3	$89.37	10.425%	$98.6868	$98.69	$98.70	$98.70
Purchase #4	$119.67	3.626%	$124.0092	$124.01	$124.00	$124.00
Purchase #5	$204.45	6.272%	$217.2731	$217.27	$217.25	$217.30
Purchase #6	$233.89	13.646%	$265.8066	$265.81	$265.80	$265.80
Purchase #7	$124.28	3.445%	$128.5614	$128.56	$128.55	$128.60
7 purchase totals =	$973.30		$1,056.9482	$1,056.96	$1,056.95	$1,057.00