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	$125.65	5.867%	$133.0219	$133.02	$133.00	$133.00
Purchase #2	$231.37	9.574%	$253.5214	$253.52	$253.50	$253.50
Purchase #3	$34.46	10.365%	$38.0318	$38.03	$38.05	$38.00
Purchase #4	$166.89	7.467%	$179.3517	$179.35	$179.35	$179.40
Purchase #5	$197.59	11.496%	$220.3049	$220.30	$220.30	$220.30
Purchase #6	$71.93	9.117%	$78.4879	$78.49	$78.50	$78.50
Purchase #7	$103.49	8.130%	$111.9037	$111.90	$111.90	$111.90
7 purchase totals =	$931.38		$1,014.6233	$1,014.61	$1,014.60	$1,014.60