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	$184.40	12.164%	$206.8304	$206.83	$206.85	$206.80
Purchase #2	$87.80	13.194%	$99.3843	$99.38	$99.40	$99.40
Purchase #3	$5.59	6.344%	$5.9446	$5.94	$5.95	$5.90
Purchase #4	$140.62	5.167%	$147.8858	$147.89	$147.90	$147.90
Purchase #5	$60.66	10.611%	$67.0966	$67.10	$67.10	$67.10
Purchase #6	$45.87	10.201%	$50.5492	$50.55	$50.55	$50.50
Purchase #7	$166.37	11.713%	$185.8569	$185.86	$185.85	$185.90
7 purchase totals =	$691.31		$763.5478	$763.55	$763.60	$763.50