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	$217.71	9.459%	$238.3032	$238.30	$238.30	$238.30
Purchase #2	$14.32	7.625%	$15.4119	$15.41	$15.40	$15.40
Purchase #3	$55.42	11.381%	$61.7274	$61.73	$61.75	$61.70
Purchase #4	$72.92	12.192%	$81.8104	$81.81	$81.80	$81.80
Purchase #5	$139.45	3.698%	$144.6069	$144.61	$144.60	$144.60
Purchase #6	$96.91	7.123%	$103.8129	$103.81	$103.80	$103.80
Purchase #7	$133.69	11.845%	$149.5256	$149.53	$149.55	$149.50
7 purchase totals =	$730.42		$795.1983	$795.20	$795.20	$795.10