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	$14.59	7.275%	$15.6514	$15.65	$15.65	$15.70
Purchase #2	$91.55	13.757%	$104.1445	$104.14	$104.15	$104.10
Purchase #3	$200.41	7.726%	$215.8937	$215.89	$215.90	$215.90
Purchase #4	$247.96	13.663%	$281.8388	$281.84	$281.85	$281.80
Purchase #5	$237.92	8.469%	$258.0694	$258.07	$258.05	$258.10
Purchase #6	$123.96	10.412%	$136.8667	$136.87	$136.85	$136.90
Purchase #7	$77.79	5.466%	$82.042	$82.04	$82.05	$82.00
7 purchase totals =	$994.18		$1,094.5065	$1,094.50	$1,094.50	$1,094.50