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	$124.63	7.175%	$133.5722	$133.57	$133.55	$133.60
Purchase #2	$88.32	12.731%	$99.564	$99.56	$99.55	$99.60
Purchase #3	$124.38	7.103%	$133.2147	$133.21	$133.20	$133.20
Purchase #4	$118.74	7.625%	$127.7939	$127.79	$127.80	$127.80
Purchase #5	$152.30	9.423%	$166.6512	$166.65	$166.65	$166.70
Purchase #6	$106.59	7.504%	$114.5885	$114.59	$114.60	$114.60
Purchase #7	$183.31	4.709%	$191.9421	$191.94	$191.95	$191.90
7 purchase totals =	$898.27		$967.3266	$967.31	$967.30	$967.40