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	$75.61	9.303%	$82.644	$82.64	$82.65	$82.60
Purchase #2	$213.61	7.627%	$229.902	$229.90	$229.90	$229.90
Purchase #3	$6.66	8.776%	$7.2445	$7.24	$7.25	$7.20
Purchase #4	$185.79	13.272%	$210.448	$210.45	$210.45	$210.40
Purchase #5	$238.33	13.788%	$271.1909	$271.19	$271.20	$271.20
Purchase #6	$227.59	12.340%	$255.6746	$255.67	$255.65	$255.70
Purchase #7	$41.96	12.681%	$47.2809	$47.28	$47.30	$47.30
7 purchase totals =	$989.55		$1,104.3849	$1,104.37	$1,104.40	$1,104.30