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	$77.36	11.636%	$86.3616	$86.36	$86.35	$86.40
Purchase #2	$93.65	10.361%	$103.3531	$103.35	$103.35	$103.40
Purchase #3	$67.75	8.220%	$73.3191	$73.32	$73.30	$73.30
Purchase #4	$249.73	4.634%	$261.3025	$261.30	$261.30	$261.30
Purchase #5	$199.63	11.474%	$222.5355	$222.54	$222.55	$222.50
Purchase #6	$105.77	9.289%	$115.595	$115.60	$115.60	$115.60
Purchase #7	$142.46	7.270%	$152.8168	$152.82	$152.80	$152.80
7 purchase totals =	$936.35		$1,015.2836	$1,015.29	$1,015.25	$1,015.30