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	$152.90	6.320%	$162.5633	$162.56	$162.55	$162.60
Purchase #2	$25.68	3.572%	$26.5973	$26.60	$26.60	$26.60
Purchase #3	$59.61	13.180%	$67.4666	$67.47	$67.45	$67.50
Purchase #4	$37.49	10.673%	$41.4913	$41.49	$41.50	$41.50
Purchase #5	$161.77	6.336%	$172.0197	$172.02	$172.00	$172.00
Purchase #6	$178.78	10.122%	$196.8761	$196.88	$196.90	$196.90
Purchase #7	$178.42	4.162%	$185.8458	$185.85	$185.85	$185.80
7 purchase totals =	$794.65		$852.8601	$852.87	$852.85	$852.90