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	$196.64	4.686%	$205.8546	$205.85	$205.85	$205.90
Purchase #2	$223.81	7.630%	$240.8867	$240.89	$240.90	$240.90
Purchase #3	$195.98	10.405%	$216.3717	$216.37	$216.35	$216.40
Purchase #4	$134.54	8.164%	$145.5238	$145.52	$145.50	$145.50
Purchase #5	$135.27	7.127%	$144.9107	$144.91	$144.90	$144.90
Purchase #6	$178.44	5.639%	$188.5022	$188.50	$188.50	$188.50
Purchase #7	$110.31	8.118%	$119.265	$119.27	$119.25	$119.30
7 purchase totals =	$1,174.99		$1,261.3147	$1,261.31	$1,261.25	$1,261.40