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	$53.31	4.482%	$55.6994	$55.70	$55.70	$55.70
Purchase #2	$95.36	5.692%	$100.7879	$100.79	$100.80	$100.80
Purchase #3	$234.42	3.464%	$242.5403	$242.54	$242.55	$242.50
Purchase #4	$80.86	9.426%	$88.4819	$88.48	$88.50	$88.50
Purchase #5	$27.28	3.707%	$28.2913	$28.29	$28.30	$28.30
Purchase #6	$90.77	3.190%	$93.6656	$93.67	$93.65	$93.70
Purchase #7	$87.54	9.151%	$95.5508	$95.55	$95.55	$95.60
7 purchase totals =	$669.54		$705.0172	$705.02	$705.05	$705.10