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	$175.50	11.564%	$195.7948	$195.79	$195.80	$195.80
Purchase #2	$90.93	13.308%	$103.031	$103.03	$103.05	$103.00
Purchase #3	$130.28	9.466%	$142.6123	$142.61	$142.60	$142.60
Purchase #4	$143.30	6.667%	$152.8538	$152.85	$152.85	$152.90
Purchase #5	$200.99	8.813%	$218.7032	$218.70	$218.70	$218.70
Purchase #6	$216.59	12.494%	$243.6508	$243.65	$243.65	$243.70
Purchase #7	$66.60	6.480%	$70.9157	$70.92	$70.90	$70.90
7 purchase totals =	$1,024.19		$1,127.5616	$1,127.55	$1,127.55	$1,127.60