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	$201.57	5.603%	$212.864	$212.86	$212.85	$212.90
Purchase #2	$114.76	7.301%	$123.1386	$123.14	$123.15	$123.10
Purchase #3	$119.77	12.609%	$134.8718	$134.87	$134.85	$134.90
Purchase #4	$130.28	8.692%	$141.6039	$141.60	$141.60	$141.60
Purchase #5	$244.33	6.355%	$259.8572	$259.86	$259.85	$259.90
Purchase #6	$94.61	7.453%	$101.6613	$101.66	$101.65	$101.70
Purchase #7	$66.47	7.579%	$71.5078	$71.51	$71.50	$71.50
7 purchase totals =	$971.79		$1,045.5046	$1,045.50	$1,045.45	$1,045.60