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	$207.92	7.474%	$223.4599	$223.46	$223.45	$223.50
Purchase #2	$54.33	10.303%	$59.9276	$59.93	$59.95	$59.90
Purchase #3	$200.37	10.287%	$220.9821	$220.98	$221.00	$221.00
Purchase #4	$110.95	4.831%	$116.31	$116.31	$116.30	$116.30
Purchase #5	$94.68	4.135%	$98.595	$98.60	$98.60	$98.60
Purchase #6	$224.32	4.441%	$234.2821	$234.28	$234.30	$234.30
Purchase #7	$142.70	9.717%	$156.5662	$156.57	$156.55	$156.60
7 purchase totals =	$1,035.27		$1,110.1229	$1,110.13	$1,110.15	$1,110.20