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	$152.62	7.713%	$164.3916	$164.39	$164.40	$164.40
Purchase #2	$148.36	10.767%	$164.3339	$164.33	$164.35	$164.30
Purchase #3	$83.31	4.217%	$86.8232	$86.82	$86.80	$86.80
Purchase #4	$163.73	4.629%	$171.3091	$171.31	$171.30	$171.30
Purchase #5	$152.54	5.714%	$161.2561	$161.26	$161.25	$161.30
Purchase #6	$151.71	7.727%	$163.4326	$163.43	$163.45	$163.40
Purchase #7	$97.49	7.608%	$104.907	$104.91	$104.90	$104.90
7 purchase totals =	$949.76		$1,016.4535	$1,016.45	$1,016.45	$1,016.40