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	$69.56	4.264%	$72.526	$72.53	$72.55	$72.50
Purchase #2	$231.81	7.285%	$248.6974	$248.70	$248.70	$248.70
Purchase #3	$147.91	11.118%	$164.3546	$164.35	$164.35	$164.40
Purchase #4	$62.37	3.272%	$64.4107	$64.41	$64.40	$64.40
Purchase #5	$104.60	6.668%	$111.5747	$111.57	$111.55	$111.60
Purchase #6	$121.95	5.514%	$128.6743	$128.67	$128.65	$128.70
Purchase #7	$18.93	3.188%	$19.5335	$19.53	$19.55	$19.50
7 purchase totals =	$757.13		$809.7712	$809.76	$809.75	$809.80