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	$101.28	4.865%	$106.2073	$106.21	$106.20	$106.20
Purchase #2	$22.50	13.863%	$25.6192	$25.62	$25.60	$25.60
Purchase #3	$86.79	3.619%	$89.9309	$89.93	$89.95	$89.90
Purchase #4	$85.62	13.740%	$97.3842	$97.38	$97.40	$97.40
Purchase #5	$172.43	9.155%	$188.216	$188.22	$188.20	$188.20
Purchase #6	$168.49	13.786%	$191.718	$191.72	$191.70	$191.70
Purchase #7	$176.56	11.374%	$196.6419	$196.64	$196.65	$196.60
7 purchase totals =	$813.67		$895.7175	$895.72	$895.70	$895.60