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	$92.95	12.868%	$104.9108	$104.91	$104.90	$104.90
Purchase #2	$134.66	12.842%	$151.953	$151.95	$151.95	$152.00
Purchase #3	$235.71	8.347%	$255.3847	$255.38	$255.40	$255.40
Purchase #4	$116.98	8.579%	$127.0157	$127.02	$127.00	$127.00
Purchase #5	$157.49	4.427%	$164.4621	$164.46	$164.45	$164.50
Purchase #6	$71.37	10.799%	$79.0772	$79.08	$79.10	$79.10
Purchase #7	$157.68	8.676%	$171.3603	$171.36	$171.35	$171.40
7 purchase totals =	$966.84		$1,054.1638	$1,054.16	$1,054.15	$1,054.30