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	$171.39	6.226%	$182.0607	$182.06	$182.05	$182.10
Purchase #2	$69.92	12.398%	$78.5887	$78.59	$78.60	$78.60
Purchase #3	$99.87	11.316%	$111.1713	$111.17	$111.15	$111.20
Purchase #4	$192.99	12.165%	$216.4672	$216.47	$216.45	$216.50
Purchase #5	$181.56	8.580%	$197.1378	$197.14	$197.15	$197.10
Purchase #6	$145.49	11.669%	$162.4672	$162.47	$162.45	$162.50
Purchase #7	$161.50	3.731%	$167.5256	$167.53	$167.55	$167.50
7 purchase totals =	$1,022.72		$1,115.4185	$1,115.43	$1,115.40	$1,115.50