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	$167.67	10.774%	$185.7348	$185.73	$185.75	$185.70
Purchase #2	$17.86	5.325%	$18.811	$18.81	$18.80	$18.80
Purchase #3	$67.32	8.138%	$72.7985	$72.80	$72.80	$72.80
Purchase #4	$210.25	4.523%	$219.7596	$219.76	$219.75	$219.80
Purchase #5	$144.59	6.470%	$153.945	$153.95	$153.95	$153.90
Purchase #6	$184.92	5.496%	$195.0832	$195.08	$195.10	$195.10
Purchase #7	$147.60	5.777%	$156.1269	$156.13	$156.15	$156.10
7 purchase totals =	$940.21		$1,002.2590	$1,002.26	$1,002.30	$1,002.20