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	$224.74	8.689%	$244.2677	$244.27	$244.25	$244.30
Purchase #2	$218.46	5.266%	$229.9641	$229.96	$229.95	$230.00
Purchase #3	$150.49	12.484%	$169.2772	$169.28	$169.30	$169.30
Purchase #4	$13.85	6.514%	$14.7522	$14.75	$14.75	$14.80
Purchase #5	$32.77	3.558%	$33.936	$33.94	$33.95	$33.90
Purchase #6	$193.34	3.852%	$200.7875	$200.79	$200.80	$200.80
Purchase #7	$96.27	13.123%	$108.9035	$108.90	$108.90	$108.90
7 purchase totals =	$929.92		$1,001.8882	$1,001.89	$1,001.90	$1,002.00