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	$208.94	11.633%	$233.246	$233.25	$233.25	$233.20
Purchase #2	$138.87	12.435%	$156.1385	$156.14	$156.15	$156.10
Purchase #3	$189.46	11.357%	$210.977	$210.98	$211.00	$211.00
Purchase #4	$222.79	4.569%	$232.9693	$232.97	$232.95	$233.00
Purchase #5	$28.32	7.353%	$30.4024	$30.40	$30.40	$30.40
Purchase #6	$50.50	6.254%	$53.6583	$53.66	$53.65	$53.70
Purchase #7	$89.72	10.594%	$99.2249	$99.22	$99.20	$99.20
7 purchase totals =	$928.60		$1,016.6164	$1,016.62	$1,016.60	$1,016.60