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	$69.95	10.507%	$77.2996	$77.30	$77.30	$77.30
Purchase #2	$164.78	10.344%	$181.8248	$181.82	$181.80	$181.80
Purchase #3	$221.89	9.640%	$243.2802	$243.28	$243.30	$243.30
Purchase #4	$207.34	5.601%	$218.9531	$218.95	$218.95	$219.00
Purchase #5	$56.83	8.385%	$61.5952	$61.60	$61.60	$61.60
Purchase #6	$96.93	8.209%	$104.887	$104.89	$104.90	$104.90
Purchase #7	$156.67	6.453%	$166.7799	$166.78	$166.80	$166.80
7 purchase totals =	$974.39		$1,054.6198	$1,054.62	$1,054.65	$1,054.70