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	$140.78	7.234%	$150.964	$150.96	$150.95	$151.00
Purchase #2	$36.81	12.335%	$41.3505	$41.35	$41.35	$41.40
Purchase #3	$187.63	8.657%	$203.8731	$203.87	$203.85	$203.90
Purchase #4	$149.40	6.331%	$158.8585	$158.86	$158.85	$158.90
Purchase #5	$127.78	12.314%	$143.5148	$143.51	$143.50	$143.50
Purchase #6	$236.82	7.582%	$254.7757	$254.78	$254.80	$254.80
Purchase #7	$200.60	11.119%	$222.9047	$222.90	$222.90	$222.90
7 purchase totals =	$1,079.82		$1,176.2413	$1,176.23	$1,176.20	$1,176.40