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	$229.63	9.625%	$251.7319	$251.73	$251.75	$251.70
Purchase #2	$231.25	9.803%	$253.9194	$253.92	$253.90	$253.90
Purchase #3	$152.48	13.136%	$172.5098	$172.51	$172.50	$172.50
Purchase #4	$79.64	3.389%	$82.339	$82.34	$82.35	$82.30
Purchase #5	$40.49	12.836%	$45.6873	$45.69	$45.70	$45.70
Purchase #6	$184.85	10.328%	$203.9413	$203.94	$203.95	$203.90
Purchase #7	$98.55	5.847%	$104.3122	$104.31	$104.30	$104.30
7 purchase totals =	$1,016.89		$1,114.4409	$1,114.44	$1,114.45	$1,114.30