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	$130.86	11.510%	$145.922	$145.92	$145.90	$145.90
Purchase #2	$88.63	7.551%	$95.3225	$95.32	$95.30	$95.30
Purchase #3	$24.48	7.583%	$26.3363	$26.34	$26.35	$26.30
Purchase #4	$110.88	6.325%	$117.8932	$117.89	$117.90	$117.90
Purchase #5	$123.67	8.802%	$134.5554	$134.56	$134.55	$134.60
Purchase #6	$53.79	10.552%	$59.4659	$59.47	$59.45	$59.50
Purchase #7	$169.69	3.553%	$175.7191	$175.72	$175.70	$175.70
7 purchase totals =	$702.00		$755.2144	$755.22	$755.15	$755.20