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	$85.65	9.181%	$93.5135	$93.51	$93.50	$93.50
Purchase #2	$82.56	10.873%	$91.5367	$91.54	$91.55	$91.50
Purchase #3	$106.72	9.594%	$116.9587	$116.96	$116.95	$117.00
Purchase #4	$123.59	12.841%	$139.4602	$139.46	$139.45	$139.50
Purchase #5	$242.99	5.160%	$255.5283	$255.53	$255.55	$255.50
Purchase #6	$105.31	12.654%	$118.6359	$118.64	$118.65	$118.60
Purchase #7	$216.32	10.321%	$238.6464	$238.65	$238.65	$238.60
7 purchase totals =	$963.14		$1,054.2797	$1,054.29	$1,054.30	$1,054.20