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	$213.96	11.455%	$238.4691	$238.47	$238.45	$238.50
Purchase #2	$229.73	12.627%	$258.738	$258.74	$258.75	$258.70
Purchase #3	$60.34	3.674%	$62.5569	$62.56	$62.55	$62.60
Purchase #4	$38.56	4.662%	$40.3577	$40.36	$40.35	$40.40
Purchase #5	$132.97	4.189%	$138.5401	$138.54	$138.55	$138.50
Purchase #6	$93.85	8.569%	$101.892	$101.89	$101.90	$101.90
Purchase #7	$196.51	7.263%	$210.7825	$210.78	$210.80	$210.80
7 purchase totals =	$965.92		$1,051.3363	$1,051.34	$1,051.35	$1,051.40