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	$57.53	9.231%	$62.8406	$62.84	$62.85	$62.80
Purchase #2	$81.32	12.138%	$91.1906	$91.19	$91.20	$91.20
Purchase #3	$191.32	3.613%	$198.2324	$198.23	$198.25	$198.20
Purchase #4	$241.53	3.318%	$249.544	$249.54	$249.55	$249.50
Purchase #5	$78.48	12.382%	$88.1974	$88.20	$88.20	$88.20
Purchase #6	$72.32	11.845%	$80.8863	$80.89	$80.90	$80.90
Purchase #7	$233.89	12.464%	$263.042	$263.04	$263.05	$263.00
7 purchase totals =	$956.39		$1,033.9333	$1,033.93	$1,034.00	$1,033.80