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	$114.61	11.202%	$127.4486	$127.45	$127.45	$127.40
Purchase #2	$235.86	8.806%	$256.6298	$256.63	$256.65	$256.60
Purchase #3	$5.45	8.574%	$5.9173	$5.92	$5.90	$5.90
Purchase #4	$73.81	7.801%	$79.5679	$79.57	$79.55	$79.60
Purchase #5	$242.47	6.859%	$259.101	$259.10	$259.10	$259.10
Purchase #6	$114.73	9.321%	$125.424	$125.42	$125.40	$125.40
Purchase #7	$180.73	8.571%	$196.2204	$196.22	$196.20	$196.20
7 purchase totals =	$967.66		$1,050.3090	$1,050.31	$1,050.25	$1,050.20