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	$199.28	11.329%	$221.8564	$221.86	$221.85	$221.90
Purchase #2	$5.82	8.342%	$6.3055	$6.31	$6.30	$6.30
Purchase #3	$188.73	10.277%	$208.1258	$208.13	$208.15	$208.10
Purchase #4	$38.28	10.648%	$42.3561	$42.36	$42.35	$42.40
Purchase #5	$164.25	3.587%	$170.1416	$170.14	$170.15	$170.10
Purchase #6	$82.56	10.653%	$91.3551	$91.36	$91.35	$91.40
Purchase #7	$244.66	10.140%	$269.4685	$269.47	$269.45	$269.50
7 purchase totals =	$923.58		$1,009.6090	$1,009.63	$1,009.60	$1,009.70