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	$113.53	4.331%	$118.447	$118.45	$118.45	$118.40
Purchase #2	$31.89	6.163%	$33.8554	$33.86	$33.85	$33.90
Purchase #3	$82.50	5.406%	$86.96	$86.96	$86.95	$87.00
Purchase #4	$224.80	3.162%	$231.9082	$231.91	$231.90	$231.90
Purchase #5	$188.25	11.809%	$210.4804	$210.48	$210.50	$210.50
Purchase #6	$168.41	4.454%	$175.911	$175.91	$175.90	$175.90
Purchase #7	$205.57	6.598%	$219.1335	$219.13	$219.15	$219.10
7 purchase totals =	$1,014.95		$1,076.6955	$1,076.70	$1,076.70	$1,076.70