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	$178.86	10.421%	$197.499	$197.50	$197.50	$197.50
Purchase #2	$10.31	10.637%	$11.4067	$11.41	$11.40	$11.40
Purchase #3	$115.89	13.158%	$131.1388	$131.14	$131.15	$131.10
Purchase #4	$170.49	11.209%	$189.6002	$189.60	$189.60	$189.60
Purchase #5	$186.95	10.249%	$206.1105	$206.11	$206.10	$206.10
Purchase #6	$134.74	11.724%	$150.5369	$150.54	$150.55	$150.50
Purchase #7	$82.80	3.225%	$85.4703	$85.47	$85.45	$85.50
7 purchase totals =	$880.04		$971.7624	$971.77	$971.75	$971.70