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	$76.48	11.655%	$85.3937	$85.39	$85.40	$85.40
Purchase #2	$201.54	11.263%	$224.2395	$224.24	$224.25	$224.20
Purchase #3	$60.89	7.184%	$65.2643	$65.26	$65.25	$65.30
Purchase #4	$98.33	6.213%	$104.4392	$104.44	$104.45	$104.40
Purchase #5	$247.53	3.585%	$256.404	$256.40	$256.40	$256.40
Purchase #6	$202.32	5.699%	$213.8502	$213.85	$213.85	$213.90
Purchase #7	$216.48	4.173%	$225.5137	$225.51	$225.50	$225.50
7 purchase totals =	$1,103.57		$1,175.1046	$1,175.09	$1,175.10	$1,175.10