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	$196.86	9.813%	$216.1779	$216.18	$216.20	$216.20
Purchase #2	$172.59	5.688%	$182.4069	$182.41	$182.40	$182.40
Purchase #3	$162.63	10.302%	$179.3841	$179.38	$179.40	$179.40
Purchase #4	$208.80	13.421%	$236.823	$236.82	$236.80	$236.80
Purchase #5	$151.27	8.477%	$164.0932	$164.09	$164.10	$164.10
Purchase #6	$56.46	5.377%	$59.4959	$59.50	$59.50	$59.50
Purchase #7	$121.93	6.668%	$130.0603	$130.06	$130.05	$130.10
7 purchase totals =	$1,070.54		$1,168.4413	$1,168.44	$1,168.45	$1,168.50