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	$163.75	11.249%	$182.1702	$182.17	$182.15	$182.20
Purchase #2	$31.59	4.139%	$32.8975	$32.90	$32.90	$32.90
Purchase #3	$142.31	9.190%	$155.3883	$155.39	$155.40	$155.40
Purchase #4	$202.61	6.869%	$216.5273	$216.53	$216.55	$216.50
Purchase #5	$232.66	7.666%	$250.4957	$250.50	$250.50	$250.50
Purchase #6	$38.42	6.555%	$40.9384	$40.94	$40.95	$40.90
Purchase #7	$127.97	6.147%	$135.8363	$135.84	$135.85	$135.80
7 purchase totals =	$939.31		$1,014.2537	$1,014.27	$1,014.30	$1,014.20