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	$182.61	7.315%	$195.9679	$195.97	$195.95	$196.00
Purchase #2	$105.77	5.269%	$111.343	$111.34	$111.35	$111.30
Purchase #3	$87.88	5.389%	$92.6159	$92.62	$92.60	$92.60
Purchase #4	$55.72	3.140%	$57.4696	$57.47	$57.45	$57.50
Purchase #5	$39.28	6.625%	$41.8823	$41.88	$41.90	$41.90
Purchase #6	$172.64	12.698%	$194.5618	$194.56	$194.55	$194.60
Purchase #7	$145.44	7.669%	$156.5938	$156.59	$156.60	$156.60
7 purchase totals =	$789.34		$850.4343	$850.43	$850.40	$850.50