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	$182.93	7.654%	$196.9315	$196.93	$196.95	$196.90
Purchase #2	$230.56	11.854%	$257.8906	$257.89	$257.90	$257.90
Purchase #3	$83.29	3.194%	$85.9503	$85.95	$85.95	$86.00
Purchase #4	$10.50	8.869%	$11.4312	$11.43	$11.45	$11.40
Purchase #5	$41.62	11.280%	$46.3147	$46.31	$46.30	$46.30
Purchase #6	$5.73	9.682%	$6.2848	$6.28	$6.30	$6.30
Purchase #7	$238.60	4.172%	$248.5544	$248.55	$248.55	$248.60
7 purchase totals =	$793.23		$853.3575	$853.34	$853.40	$853.40