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	$55.64	9.544%	$60.9503	$60.95	$60.95	$61.00
Purchase #2	$20.61	4.520%	$21.5416	$21.54	$21.55	$21.50
Purchase #3	$81.90	12.766%	$92.3554	$92.36	$92.35	$92.40
Purchase #4	$130.83	13.718%	$148.7773	$148.78	$148.80	$148.80
Purchase #5	$57.41	13.733%	$65.2941	$65.29	$65.30	$65.30
Purchase #6	$40.87	7.377%	$43.885	$43.89	$43.90	$43.90
Purchase #7	$229.40	13.518%	$260.4103	$260.41	$260.40	$260.40
7 purchase totals =	$616.66		$693.2140	$693.22	$693.25	$693.30