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	$216.43	5.502%	$228.338	$228.34	$228.35	$228.30
Purchase #2	$98.34	6.484%	$104.7164	$104.72	$104.70	$104.70
Purchase #3	$86.89	10.122%	$95.685	$95.69	$95.70	$95.70
Purchase #4	$227.60	4.803%	$238.5316	$238.53	$238.55	$238.50
Purchase #5	$224.69	13.463%	$254.94	$254.94	$254.95	$254.90
Purchase #6	$221.91	5.730%	$234.6254	$234.63	$234.65	$234.60
Purchase #7	$78.78	10.365%	$86.9455	$86.95	$86.95	$86.90
7 purchase totals =	$1,154.64		$1,243.7819	$1,243.80	$1,243.85	$1,243.60