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	$230.44	4.794%	$241.4873	$241.49	$241.50	$241.50
Purchase #2	$187.36	5.117%	$196.9472	$196.95	$196.95	$196.90
Purchase #3	$25.52	10.384%	$28.17	$28.17	$28.15	$28.20
Purchase #4	$64.60	5.650%	$68.2499	$68.25	$68.25	$68.20
Purchase #5	$114.92	8.674%	$124.8882	$124.89	$124.90	$124.90
Purchase #6	$102.77	6.340%	$109.2856	$109.29	$109.30	$109.30
Purchase #7	$240.81	5.654%	$254.4254	$254.43	$254.45	$254.40
7 purchase totals =	$966.42		$1,023.4536	$1,023.47	$1,023.50	$1,023.40