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	$86.74	9.534%	$95.0098	$95.01	$95.00	$95.00
Purchase #2	$232.31	10.158%	$255.908	$255.91	$255.90	$255.90
Purchase #3	$55.77	12.540%	$62.7636	$62.76	$62.75	$62.80
Purchase #4	$147.86	11.684%	$165.136	$165.14	$165.15	$165.10
Purchase #5	$135.58	4.816%	$142.1095	$142.11	$142.10	$142.10
Purchase #6	$144.88	7.225%	$155.3476	$155.35	$155.35	$155.30
Purchase #7	$118.50	4.502%	$123.8349	$123.83	$123.85	$123.80
7 purchase totals =	$921.64		$1,000.1094	$1,000.11	$1,000.10	$1,000.00