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	$54.36	9.196%	$59.3589	$59.36	$59.35	$59.40
Purchase #2	$103.41	6.812%	$110.4543	$110.45	$110.45	$110.50
Purchase #3	$118.57	5.227%	$124.7677	$124.77	$124.75	$124.80
Purchase #4	$153.72	12.861%	$173.4899	$173.49	$173.50	$173.50
Purchase #5	$196.61	4.445%	$205.3493	$205.35	$205.35	$205.30
Purchase #6	$145.97	4.768%	$152.9298	$152.93	$152.95	$152.90
Purchase #7	$195.75	5.512%	$206.5397	$206.54	$206.55	$206.50
7 purchase totals =	$968.39		$1,032.8896	$1,032.89	$1,032.90	$1,032.90