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	$224.76	4.656%	$235.2248	$235.22	$235.20	$235.20
Purchase #2	$153.87	4.498%	$160.7911	$160.79	$160.80	$160.80
Purchase #3	$87.45	3.377%	$90.4032	$90.40	$90.40	$90.40
Purchase #4	$193.90	7.849%	$209.1192	$209.12	$209.10	$209.10
Purchase #5	$6.34	11.533%	$7.0712	$7.07	$7.05	$7.10
Purchase #6	$141.77	3.532%	$146.7773	$146.78	$146.80	$146.80
Purchase #7	$155.66	6.761%	$166.1842	$166.18	$166.20	$166.20
7 purchase totals =	$963.75		$1,015.5710	$1,015.56	$1,015.55	$1,015.60