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	$173.68	8.481%	$188.4098	$188.41	$188.40	$188.40
Purchase #2	$90.70	10.854%	$100.5446	$100.54	$100.55	$100.50
Purchase #3	$63.77	6.284%	$67.7773	$67.78	$67.80	$67.80
Purchase #4	$65.99	13.628%	$74.9831	$74.98	$75.00	$75.00
Purchase #5	$242.88	10.604%	$268.635	$268.64	$268.65	$268.60
Purchase #6	$191.60	4.705%	$200.6148	$200.61	$200.60	$200.60
Purchase #7	$183.29	5.759%	$193.8457	$193.85	$193.85	$193.80
7 purchase totals =	$1,011.91		$1,094.8103	$1,094.81	$1,094.85	$1,094.70