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	$219.64	3.738%	$227.8501	$227.85	$227.85	$227.90
Purchase #2	$248.84	11.464%	$277.367	$277.37	$277.35	$277.40
Purchase #3	$154.98	7.576%	$166.7213	$166.72	$166.70	$166.70
Purchase #4	$238.54	10.351%	$263.2313	$263.23	$263.25	$263.20
Purchase #5	$190.25	4.675%	$199.1442	$199.14	$199.15	$199.10
Purchase #6	$54.34	13.146%	$61.4835	$61.48	$61.50	$61.50
Purchase #7	$93.45	3.293%	$96.5273	$96.53	$96.55	$96.50
7 purchase totals =	$1,200.04		$1,292.3247	$1,292.32	$1,292.35	$1,292.30