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	$113.62	11.305%	$126.4647	$126.46	$126.45	$126.50
Purchase #2	$93.69	7.678%	$100.8835	$100.88	$100.90	$100.90
Purchase #3	$48.42	9.733%	$53.1327	$53.13	$53.15	$53.10
Purchase #4	$99.69	12.362%	$112.0137	$112.01	$112.00	$112.00
Purchase #5	$195.38	9.473%	$213.8883	$213.89	$213.90	$213.90
Purchase #6	$151.91	9.704%	$166.6513	$166.65	$166.65	$166.70
Purchase #7	$85.80	7.243%	$92.0145	$92.01	$92.00	$92.00
7 purchase totals =	$788.51		$865.0487	$865.03	$865.05	$865.10