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	$176.32	13.615%	$200.326	$200.33	$200.35	$200.30
Purchase #2	$50.40	4.424%	$52.6297	$52.63	$52.65	$52.60
Purchase #3	$94.76	11.570%	$105.7237	$105.72	$105.70	$105.70
Purchase #4	$24.78	8.610%	$26.9136	$26.91	$26.90	$26.90
Purchase #5	$189.89	5.404%	$200.1517	$200.15	$200.15	$200.20
Purchase #6	$160.96	5.234%	$169.3846	$169.38	$169.40	$169.40
Purchase #7	$54.70	7.870%	$59.0049	$59.00	$59.00	$59.00
7 purchase totals =	$751.81		$814.1342	$814.12	$814.15	$814.10