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	$95.71	9.685%	$104.9795	$104.98	$105.00	$105.00
Purchase #2	$138.27	4.478%	$144.4617	$144.46	$144.45	$144.50
Purchase #3	$166.51	8.817%	$181.1912	$181.19	$181.20	$181.20
Purchase #4	$42.96	6.735%	$45.8534	$45.85	$45.85	$45.90
Purchase #5	$237.88	11.352%	$264.8841	$264.88	$264.90	$264.90
Purchase #6	$242.81	10.135%	$267.4188	$267.42	$267.40	$267.40
Purchase #7	$127.86	12.741%	$144.1506	$144.15	$144.15	$144.20
7 purchase totals =	$1,052.00		$1,152.9393	$1,152.93	$1,152.95	$1,153.10