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	$202.62	10.352%	$223.5952	$223.60	$223.60	$223.60
Purchase #2	$169.61	12.459%	$190.7417	$190.74	$190.75	$190.70
Purchase #3	$44.38	8.694%	$48.2384	$48.24	$48.25	$48.20
Purchase #4	$64.97	9.315%	$71.022	$71.02	$71.00	$71.00
Purchase #5	$166.45	13.235%	$188.4797	$188.48	$188.50	$188.50
Purchase #6	$65.65	10.566%	$72.5866	$72.59	$72.60	$72.60
Purchase #7	$237.65	9.863%	$261.0894	$261.09	$261.10	$261.10
7 purchase totals =	$951.33		$1,055.7530	$1,055.76	$1,055.80	$1,055.70