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	$250.58	7.633%	$269.7068	$269.71	$269.70	$269.70
Purchase #2	$64.60	7.661%	$69.549	$69.55	$69.55	$69.50
Purchase #3	$237.28	7.799%	$255.7855	$255.79	$255.80	$255.80
Purchase #4	$34.76	8.382%	$37.6736	$37.67	$37.65	$37.70
Purchase #5	$30.69	6.466%	$32.6744	$32.67	$32.65	$32.70
Purchase #6	$188.35	5.345%	$198.4173	$198.42	$198.40	$198.40
Purchase #7	$183.38	7.691%	$197.4838	$197.48	$197.50	$197.50
7 purchase totals =	$989.64		$1,061.2904	$1,061.29	$1,061.25	$1,061.30