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	$194.32	3.297%	$200.7267	$200.73	$200.75	$200.70
Purchase #2	$197.38	13.242%	$223.5171	$223.52	$223.50	$223.50
Purchase #3	$98.34	8.109%	$106.3144	$106.31	$106.30	$106.30
Purchase #4	$66.45	9.513%	$72.7714	$72.77	$72.75	$72.80
Purchase #5	$121.99	5.553%	$128.7641	$128.76	$128.75	$128.80
Purchase #6	$122.82	3.860%	$127.5609	$127.56	$127.55	$127.60
Purchase #7	$77.46	5.340%	$81.5964	$81.60	$81.60	$81.60
7 purchase totals =	$878.76		$941.2510	$941.25	$941.20	$941.30