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	$174.93	11.458%	$194.9735	$194.97	$194.95	$195.00
Purchase #2	$204.73	13.131%	$231.6131	$231.61	$231.60	$231.60
Purchase #3	$11.35	4.788%	$11.8934	$11.89	$11.90	$11.90
Purchase #4	$174.76	6.297%	$185.7646	$185.76	$185.75	$185.80
Purchase #5	$67.98	5.102%	$71.4483	$71.45	$71.45	$71.40
Purchase #6	$227.86	4.837%	$238.8816	$238.88	$238.90	$238.90
Purchase #7	$47.39	12.457%	$53.2934	$53.29	$53.30	$53.30
7 purchase totals =	$909.00		$987.8679	$987.85	$987.85	$987.90