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	$112.49	6.339%	$119.6207	$119.62	$119.60	$119.60
Purchase #2	$188.88	7.349%	$202.7608	$202.76	$202.75	$202.80
Purchase #3	$166.41	4.631%	$174.1164	$174.12	$174.10	$174.10
Purchase #4	$167.27	13.800%	$190.3533	$190.35	$190.35	$190.40
Purchase #5	$54.83	13.263%	$62.1021	$62.10	$62.10	$62.10
Purchase #6	$225.47	4.407%	$235.4065	$235.41	$235.40	$235.40
Purchase #7	$96.63	4.157%	$100.6469	$100.65	$100.65	$100.60
7 purchase totals =	$1,011.98		$1,085.0067	$1,085.01	$1,084.95	$1,085.00