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	$139.31	8.842%	$151.6278	$151.63	$151.65	$151.60
Purchase #2	$149.30	8.568%	$162.092	$162.09	$162.10	$162.10
Purchase #3	$40.40	3.694%	$41.8924	$41.89	$41.90	$41.90
Purchase #4	$163.64	10.465%	$180.7649	$180.76	$180.75	$180.80
Purchase #5	$188.61	4.236%	$196.5995	$196.60	$196.60	$196.60
Purchase #6	$182.41	13.390%	$206.8347	$206.83	$206.85	$206.80
Purchase #7	$143.77	6.378%	$152.9397	$152.94	$152.95	$152.90
7 purchase totals =	$1,007.44		$1,092.7510	$1,092.74	$1,092.80	$1,092.70