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	$141.56	7.102%	$151.6136	$151.61	$151.60	$151.60
Purchase #2	$242.82	13.555%	$275.7343	$275.73	$275.75	$275.70
Purchase #3	$188.81	4.656%	$197.601	$197.60	$197.60	$197.60
Purchase #4	$73.51	11.275%	$81.7983	$81.80	$81.80	$81.80
Purchase #5	$241.83	7.488%	$259.9382	$259.94	$259.95	$259.90
Purchase #6	$55.91	10.186%	$61.605	$61.61	$61.60	$61.60
Purchase #7	$157.83	6.633%	$168.2989	$168.30	$168.30	$168.30
7 purchase totals =	$1,102.27		$1,196.5893	$1,196.59	$1,196.60	$1,196.50