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	$246.35	6.179%	$261.572	$261.57	$261.55	$261.60
Purchase #2	$94.50	6.628%	$100.7635	$100.76	$100.75	$100.80
Purchase #3	$53.25	4.874%	$55.8454	$55.85	$55.85	$55.80
Purchase #4	$123.75	13.798%	$140.825	$140.83	$140.85	$140.80
Purchase #5	$150.71	11.317%	$167.7659	$167.77	$167.75	$167.80
Purchase #6	$172.45	10.306%	$190.2227	$190.22	$190.20	$190.20
Purchase #7	$140.79	4.644%	$147.3283	$147.33	$147.35	$147.30
7 purchase totals =	$981.80		$1,064.3228	$1,064.33	$1,064.30	$1,064.30