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	$209.98	7.491%	$225.7096	$225.71	$225.70	$225.70
Purchase #2	$199.63	9.550%	$218.6947	$218.69	$218.70	$218.70
Purchase #3	$116.79	10.838%	$129.4477	$129.45	$129.45	$129.40
Purchase #4	$166.33	11.386%	$185.2683	$185.27	$185.25	$185.30
Purchase #5	$78.85	9.339%	$86.2138	$86.21	$86.20	$86.20
Purchase #6	$157.93	13.819%	$179.7543	$179.75	$179.75	$179.80
Purchase #7	$114.43	11.271%	$127.3274	$127.33	$127.35	$127.30
7 purchase totals =	$1,043.94		$1,152.4158	$1,152.41	$1,152.40	$1,152.40