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	$237.37	3.264%	$245.1178	$245.12	$245.10	$245.10
Purchase #2	$115.69	3.147%	$119.3308	$119.33	$119.35	$119.30
Purchase #3	$191.37	10.611%	$211.6763	$211.68	$211.70	$211.70
Purchase #4	$69.44	4.541%	$72.5933	$72.59	$72.60	$72.60
Purchase #5	$53.33	7.456%	$57.3063	$57.31	$57.30	$57.30
Purchase #6	$196.76	10.428%	$217.2781	$217.28	$217.30	$217.30
Purchase #7	$134.39	10.611%	$148.6501	$148.65	$148.65	$148.70
7 purchase totals =	$998.35		$1,071.9527	$1,071.96	$1,072.00	$1,072.00