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	$215.89	13.722%	$245.5144	$245.51	$245.50	$245.50
Purchase #2	$104.86	12.830%	$118.3135	$118.31	$118.30	$118.30
Purchase #3	$181.30	5.325%	$190.9542	$190.95	$190.95	$191.00
Purchase #4	$71.47	4.106%	$74.4046	$74.40	$74.40	$74.40
Purchase #5	$199.63	8.674%	$216.9459	$216.95	$216.95	$216.90
Purchase #6	$165.43	9.516%	$181.1723	$181.17	$181.15	$181.20
Purchase #7	$114.78	3.113%	$118.3531	$118.35	$118.35	$118.40
7 purchase totals =	$1,053.36		$1,145.6580	$1,145.64	$1,145.60	$1,145.70