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	$181.41	8.222%	$196.3255	$196.33	$196.35	$196.30
Purchase #2	$95.95	5.285%	$101.021	$101.02	$101.00	$101.00
Purchase #3	$217.50	8.560%	$236.118	$236.12	$236.10	$236.10
Purchase #4	$77.52	11.704%	$86.5929	$86.59	$86.60	$86.60
Purchase #5	$167.84	10.514%	$185.4867	$185.49	$185.50	$185.50
Purchase #6	$222.89	8.786%	$242.4731	$242.47	$242.45	$242.50
Purchase #7	$72.76	6.172%	$77.2507	$77.25	$77.25	$77.30
7 purchase totals =	$1,035.87		$1,125.2679	$1,125.27	$1,125.25	$1,125.30