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	$130.63	13.274%	$147.9698	$147.97	$147.95	$148.00
Purchase #2	$72.74	4.867%	$76.2803	$76.28	$76.30	$76.30
Purchase #3	$56.56	4.683%	$59.2087	$59.21	$59.20	$59.20
Purchase #4	$28.46	10.549%	$31.4622	$31.46	$31.45	$31.50
Purchase #5	$89.26	6.500%	$95.0619	$95.06	$95.05	$95.10
Purchase #6	$195.86	11.409%	$218.2057	$218.21	$218.20	$218.20
Purchase #7	$118.51	4.395%	$123.7185	$123.72	$123.70	$123.70
7 purchase totals =	$692.02		$751.9071	$751.91	$751.85	$752.00