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	$191.55	4.740%	$200.6295	$200.63	$200.65	$200.60
Purchase #2	$48.48	7.137%	$51.94	$51.94	$51.95	$51.90
Purchase #3	$78.70	12.159%	$88.2691	$88.27	$88.25	$88.30
Purchase #4	$108.52	9.826%	$119.1832	$119.18	$119.20	$119.20
Purchase #5	$240.69	11.163%	$267.5582	$267.56	$267.55	$267.60
Purchase #6	$136.68	6.711%	$145.8526	$145.85	$145.85	$145.90
Purchase #7	$53.89	8.464%	$58.4512	$58.45	$58.45	$58.50
7 purchase totals =	$858.51		$931.8838	$931.88	$931.90	$932.00