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	$222.73	4.865%	$233.5658	$233.57	$233.55	$233.60
Purchase #2	$72.38	12.363%	$81.3283	$81.33	$81.35	$81.30
Purchase #3	$19.64	6.516%	$20.9197	$20.92	$20.90	$20.90
Purchase #4	$218.74	10.535%	$241.7843	$241.78	$241.80	$241.80
Purchase #5	$187.94	11.301%	$209.1791	$209.18	$209.20	$209.20
Purchase #6	$55.84	13.753%	$63.5197	$63.52	$63.50	$63.50
Purchase #7	$238.52	9.792%	$261.8759	$261.88	$261.90	$261.90
7 purchase totals =	$1,015.79		$1,112.1728	$1,112.18	$1,112.20	$1,112.20