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	$194.48	8.327%	$210.6743	$210.67	$210.65	$210.70
Purchase #2	$28.60	9.640%	$31.357	$31.36	$31.35	$31.40
Purchase #3	$188.43	7.870%	$203.2594	$203.26	$203.25	$203.30
Purchase #4	$21.84	12.237%	$24.5126	$24.51	$24.50	$24.50
Purchase #5	$104.56	6.584%	$111.4442	$111.44	$111.45	$111.40
Purchase #6	$159.53	6.189%	$169.4033	$169.40	$169.40	$169.40
Purchase #7	$184.28	6.478%	$196.2177	$196.22	$196.20	$196.20
7 purchase totals =	$881.72		$946.8685	$946.86	$946.80	$946.90