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	$196.82	8.492%	$213.534	$213.53	$213.55	$213.50
Purchase #2	$38.68	6.447%	$41.1737	$41.17	$41.15	$41.20
Purchase #3	$80.56	12.218%	$90.4028	$90.40	$90.40	$90.40
Purchase #4	$211.28	8.154%	$228.5078	$228.51	$228.50	$228.50
Purchase #5	$169.87	12.773%	$191.5675	$191.57	$191.55	$191.60
Purchase #6	$114.50	4.715%	$119.8987	$119.90	$119.90	$119.90
Purchase #7	$153.92	8.273%	$166.6538	$166.65	$166.65	$166.70
7 purchase totals =	$965.63		$1,051.7383	$1,051.73	$1,051.70	$1,051.80