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	$96.46	7.329%	$103.5296	$103.53	$103.55	$103.50
Purchase #2	$160.44	7.796%	$172.9479	$172.95	$172.95	$172.90
Purchase #3	$35.83	4.441%	$37.4212	$37.42	$37.40	$37.40
Purchase #4	$247.93	3.568%	$256.7761	$256.78	$256.80	$256.80
Purchase #5	$176.75	5.390%	$186.2768	$186.28	$186.30	$186.30
Purchase #6	$201.36	6.443%	$214.3336	$214.33	$214.35	$214.30
Purchase #7	$168.72	3.395%	$174.448	$174.45	$174.45	$174.40
7 purchase totals =	$1,087.49		$1,145.7332	$1,145.74	$1,145.80	$1,145.60