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	$171.71	13.496%	$194.884	$194.88	$194.90	$194.90
Purchase #2	$84.40	13.710%	$95.9712	$95.97	$95.95	$96.00
Purchase #3	$104.38	11.291%	$116.1655	$116.17	$116.15	$116.20
Purchase #4	$132.56	13.863%	$150.9368	$150.94	$150.95	$150.90
Purchase #5	$196.34	11.261%	$218.4498	$218.45	$218.45	$218.40
Purchase #6	$244.32	8.265%	$264.513	$264.51	$264.50	$264.50
Purchase #7	$132.45	11.741%	$148.001	$148.00	$148.00	$148.00
7 purchase totals =	$1,066.16		$1,188.9213	$1,188.92	$1,188.90	$1,188.90