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	$197.85	7.549%	$212.7857	$212.79	$212.80	$212.80
Purchase #2	$99.64	12.304%	$111.8997	$111.90	$111.90	$111.90
Purchase #3	$144.73	9.556%	$158.5604	$158.56	$158.55	$158.60
Purchase #4	$147.48	13.715%	$167.7069	$167.71	$167.70	$167.70
Purchase #5	$139.53	12.813%	$157.408	$157.41	$157.40	$157.40
Purchase #6	$197.27	11.799%	$220.5459	$220.55	$220.55	$220.50
Purchase #7	$147.92	12.626%	$166.5964	$166.60	$166.60	$166.60
7 purchase totals =	$1,074.42		$1,195.5030	$1,195.52	$1,195.50	$1,195.50