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	$140.33	7.633%	$151.0414	$151.04	$151.05	$151.00
Purchase #2	$45.98	6.252%	$48.8547	$48.85	$48.85	$48.90
Purchase #3	$146.26	10.332%	$161.3716	$161.37	$161.35	$161.40
Purchase #4	$209.39	6.197%	$222.3659	$222.37	$222.35	$222.40
Purchase #5	$230.63	8.402%	$250.0075	$250.01	$250.00	$250.00
Purchase #6	$116.69	5.798%	$123.4557	$123.46	$123.45	$123.50
Purchase #7	$135.56	3.146%	$139.8247	$139.82	$139.80	$139.80
7 purchase totals =	$1,024.84		$1,096.9215	$1,096.92	$1,096.85	$1,097.00