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	$174.46	9.843%	$191.6321	$191.63	$191.65	$191.60
Purchase #2	$233.64	3.377%	$241.53	$241.53	$241.55	$241.50
Purchase #3	$201.98	11.811%	$225.8359	$225.84	$225.85	$225.80
Purchase #4	$62.32	11.612%	$69.5566	$69.56	$69.55	$69.60
Purchase #5	$109.67	5.405%	$115.5977	$115.60	$115.60	$115.60
Purchase #6	$165.56	11.465%	$184.5415	$184.54	$184.55	$184.50
Purchase #7	$46.68	13.659%	$53.056	$53.06	$53.05	$53.10
7 purchase totals =	$994.31		$1,081.7498	$1,081.76	$1,081.80	$1,081.70