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	$196.96	7.518%	$211.7675	$211.77	$211.75	$211.80
Purchase #2	$52.58	12.367%	$59.0826	$59.08	$59.10	$59.10
Purchase #3	$30.94	6.213%	$32.8623	$32.86	$32.85	$32.90
Purchase #4	$80.42	5.740%	$85.0361	$85.04	$85.05	$85.00
Purchase #5	$216.42	9.197%	$236.3241	$236.32	$236.30	$236.30
Purchase #6	$124.69	11.795%	$139.3972	$139.40	$139.40	$139.40
Purchase #7	$208.98	10.264%	$230.4297	$230.43	$230.45	$230.40
7 purchase totals =	$910.99		$994.8995	$994.90	$994.90	$994.90