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	$196.59	7.825%	$211.9732	$211.97	$211.95	$212.00
Purchase #2	$110.27	10.741%	$122.1141	$122.11	$122.10	$122.10
Purchase #3	$24.71	3.225%	$25.5069	$25.51	$25.50	$25.50
Purchase #4	$159.65	6.572%	$170.1422	$170.14	$170.15	$170.10
Purchase #5	$136.46	6.190%	$144.9069	$144.91	$144.90	$144.90
Purchase #6	$75.27	4.286%	$78.4961	$78.50	$78.50	$78.50
Purchase #7	$143.98	12.794%	$162.4008	$162.40	$162.40	$162.40
7 purchase totals =	$846.93		$915.5402	$915.54	$915.50	$915.50