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	$86.47	10.590%	$95.6272	$95.63	$95.65	$95.60
Purchase #2	$25.65	12.385%	$28.8268	$28.83	$28.85	$28.80
Purchase #3	$201.98	9.588%	$221.3458	$221.35	$221.35	$221.30
Purchase #4	$175.80	5.532%	$185.5253	$185.53	$185.55	$185.50
Purchase #5	$36.29	13.668%	$41.2501	$41.25	$41.25	$41.30
Purchase #6	$200.31	11.145%	$222.6345	$222.63	$222.65	$222.60
Purchase #7	$201.61	11.324%	$224.4403	$224.44	$224.45	$224.40
7 purchase totals =	$928.11		$1,019.6500	$1,019.66	$1,019.75	$1,019.50