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	$175.70	5.526%	$185.4092	$185.41	$185.40	$185.40
Purchase #2	$44.78	6.327%	$47.6132	$47.61	$47.60	$47.60
Purchase #3	$224.94	7.380%	$241.5406	$241.54	$241.55	$241.50
Purchase #4	$181.43	5.737%	$191.8386	$191.84	$191.85	$191.80
Purchase #5	$49.80	12.415%	$55.9827	$55.98	$56.00	$56.00
Purchase #6	$142.91	7.683%	$153.8898	$153.89	$153.90	$153.90
Purchase #7	$125.34	11.803%	$140.1339	$140.13	$140.15	$140.10
7 purchase totals =	$944.90		$1,016.4080	$1,016.40	$1,016.45	$1,016.30