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	$182.94	4.402%	$190.993	$190.99	$191.00	$191.00
Purchase #2	$44.58	10.667%	$49.3353	$49.34	$49.35	$49.30
Purchase #3	$34.46	8.358%	$37.3402	$37.34	$37.35	$37.30
Purchase #4	$111.76	4.333%	$116.6026	$116.60	$116.60	$116.60
Purchase #5	$40.40	11.282%	$44.9579	$44.96	$44.95	$45.00
Purchase #6	$128.76	12.560%	$144.9323	$144.93	$144.95	$144.90
Purchase #7	$156.42	10.836%	$173.3697	$173.37	$173.35	$173.40
7 purchase totals =	$699.32		$757.5310	$757.53	$757.55	$757.50