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	$91.90	8.280%	$99.5093	$99.51	$99.50	$99.50
Purchase #2	$71.43	7.769%	$76.9794	$76.98	$77.00	$77.00
Purchase #3	$95.72	4.533%	$100.059	$100.06	$100.05	$100.10
Purchase #4	$127.88	13.526%	$145.177	$145.18	$145.20	$145.20
Purchase #5	$232.80	7.644%	$250.5952	$250.60	$250.60	$250.60
Purchase #6	$228.86	10.854%	$253.7005	$253.70	$253.70	$253.70
Purchase #7	$165.50	5.704%	$174.9401	$174.94	$174.95	$174.90
7 purchase totals =	$1,014.09		$1,100.9605	$1,100.97	$1,101.00	$1,101.00