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	$169.33	12.827%	$191.05	$191.05	$191.05	$191.10
Purchase #2	$6.68	10.744%	$7.3977	$7.40	$7.40	$7.40
Purchase #3	$148.38	9.485%	$162.4538	$162.45	$162.45	$162.50
Purchase #4	$82.26	13.640%	$93.4803	$93.48	$93.50	$93.50
Purchase #5	$165.89	13.730%	$188.6667	$188.67	$188.65	$188.70
Purchase #6	$131.98	7.862%	$142.3563	$142.36	$142.35	$142.40
Purchase #7	$208.49	6.596%	$222.242	$222.24	$222.25	$222.20
7 purchase totals =	$913.01		$1,007.6468	$1,007.65	$1,007.65	$1,007.80