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	$168.89	3.349%	$174.5461	$174.55	$174.55	$174.50
Purchase #2	$164.42	12.646%	$185.2126	$185.21	$185.20	$185.20
Purchase #3	$204.96	13.408%	$232.441	$232.44	$232.45	$232.40
Purchase #4	$74.41	11.584%	$83.0297	$83.03	$83.05	$83.00
Purchase #5	$172.43	8.754%	$187.5245	$187.52	$187.50	$187.50
Purchase #6	$166.59	12.272%	$187.0339	$187.03	$187.05	$187.00
Purchase #7	$71.52	8.297%	$77.454	$77.45	$77.45	$77.50
7 purchase totals =	$1,023.22		$1,127.2418	$1,127.23	$1,127.25	$1,127.10