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	$174.74	9.802%	$191.868	$191.87	$191.85	$191.90
Purchase #2	$55.80	3.395%	$57.6944	$57.69	$57.70	$57.70
Purchase #3	$52.66	12.874%	$59.4394	$59.44	$59.45	$59.40
Purchase #4	$103.63	6.821%	$110.6986	$110.70	$110.70	$110.70
Purchase #5	$24.32	13.263%	$27.5456	$27.55	$27.55	$27.50
Purchase #6	$145.58	3.832%	$151.1586	$151.16	$151.15	$151.20
Purchase #7	$166.81	12.652%	$187.9148	$187.91	$187.90	$187.90
7 purchase totals =	$723.54		$786.3194	$786.32	$786.30	$786.30