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	$174.44	10.550%	$192.8434	$192.84	$192.85	$192.80
Purchase #2	$239.70	13.426%	$271.8821	$271.88	$271.90	$271.90
Purchase #3	$144.40	10.693%	$159.8407	$159.84	$159.85	$159.80
Purchase #4	$112.59	6.144%	$119.5075	$119.51	$119.50	$119.50
Purchase #5	$57.30	13.740%	$65.173	$65.17	$65.15	$65.20
Purchase #6	$208.53	3.183%	$215.1675	$215.17	$215.15	$215.20
Purchase #7	$53.49	11.826%	$59.8157	$59.82	$59.80	$59.80
7 purchase totals =	$990.45		$1,084.2299	$1,084.23	$1,084.20	$1,084.20