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	$160.83	8.532%	$174.552	$174.55	$174.55	$174.60
Purchase #2	$132.69	13.122%	$150.1016	$150.10	$150.10	$150.10
Purchase #3	$222.50	8.490%	$241.3903	$241.39	$241.40	$241.40
Purchase #4	$10.94	8.821%	$11.905	$11.91	$11.90	$11.90
Purchase #5	$94.41	7.171%	$101.1801	$101.18	$101.20	$101.20
Purchase #6	$108.98	13.408%	$123.592	$123.59	$123.60	$123.60
Purchase #7	$190.96	6.107%	$202.6219	$202.62	$202.60	$202.60
7 purchase totals =	$921.31		$1,005.3429	$1,005.34	$1,005.35	$1,005.40