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	$92.25	9.497%	$101.011	$101.01	$101.00	$101.00
Purchase #2	$175.58	3.391%	$181.5339	$181.53	$181.55	$181.50
Purchase #3	$191.28	7.431%	$205.494	$205.49	$205.50	$205.50
Purchase #4	$32.69	5.652%	$34.5376	$34.54	$34.55	$34.50
Purchase #5	$158.31	7.114%	$169.5722	$169.57	$169.55	$169.60
Purchase #6	$33.53	12.650%	$37.7715	$37.77	$37.75	$37.80
Purchase #7	$136.73	11.119%	$151.933	$151.93	$151.95	$151.90
7 purchase totals =	$820.37		$881.8532	$881.84	$881.85	$881.80