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	$118.38	7.750%	$127.5545	$127.55	$127.55	$127.60
Purchase #2	$35.62	6.488%	$37.931	$37.93	$37.95	$37.90
Purchase #3	$49.89	4.721%	$52.2453	$52.25	$52.25	$52.20
Purchase #4	$108.50	6.580%	$115.6393	$115.64	$115.65	$115.60
Purchase #5	$152.70	11.210%	$169.8177	$169.82	$169.80	$169.80
Purchase #6	$128.41	12.599%	$144.5884	$144.59	$144.60	$144.60
Purchase #7	$143.51	12.712%	$161.753	$161.75	$161.75	$161.80
7 purchase totals =	$737.01		$809.5292	$809.53	$809.55	$809.50