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	$53.67	12.562%	$60.412	$60.41	$60.40	$60.40
Purchase #2	$77.63	7.540%	$83.4833	$83.48	$83.50	$83.50
Purchase #3	$189.47	3.821%	$196.7096	$196.71	$196.70	$196.70
Purchase #4	$228.85	9.202%	$249.9088	$249.91	$249.90	$249.90
Purchase #5	$87.56	5.763%	$92.6061	$92.61	$92.60	$92.60
Purchase #6	$59.59	9.343%	$65.1575	$65.16	$65.15	$65.20
Purchase #7	$156.81	11.572%	$174.9561	$174.96	$174.95	$175.00
7 purchase totals =	$853.58		$923.2334	$923.24	$923.20	$923.30