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	$146.37	9.650%	$160.4947	$160.49	$160.50	$160.50
Purchase #2	$7.82	4.821%	$8.197	$8.20	$8.20	$8.20
Purchase #3	$208.36	5.262%	$219.3239	$219.32	$219.30	$219.30
Purchase #4	$183.91	6.796%	$196.4085	$196.41	$196.40	$196.40
Purchase #5	$134.56	5.530%	$142.0012	$142.00	$142.00	$142.00
Purchase #6	$212.95	3.178%	$219.7176	$219.72	$219.70	$219.70
Purchase #7	$141.33	12.845%	$159.4838	$159.48	$159.50	$159.50
7 purchase totals =	$1,035.30		$1,105.6267	$1,105.62	$1,105.60	$1,105.60