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	$192.95	3.830%	$200.34	$200.34	$200.35	$200.30
Purchase #2	$82.33	12.697%	$92.7834	$92.78	$92.80	$92.80
Purchase #3	$181.89	5.600%	$192.0758	$192.08	$192.10	$192.10
Purchase #4	$41.91	5.651%	$44.2783	$44.28	$44.30	$44.30
Purchase #5	$69.60	11.608%	$77.6792	$77.68	$77.70	$77.70
Purchase #6	$157.40	13.674%	$178.9229	$178.92	$178.90	$178.90
Purchase #7	$215.25	4.680%	$225.3237	$225.32	$225.30	$225.30
7 purchase totals =	$941.33		$1,011.4033	$1,011.40	$1,011.45	$1,011.40