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	$247.73	5.820%	$262.1479	$262.15	$262.15	$262.10
Purchase #2	$88.89	7.490%	$95.5479	$95.55	$95.55	$95.50
Purchase #3	$72.54	13.595%	$82.4018	$82.40	$82.40	$82.40
Purchase #4	$164.87	12.162%	$184.9215	$184.92	$184.90	$184.90
Purchase #5	$50.39	13.278%	$57.0808	$57.08	$57.10	$57.10
Purchase #6	$236.84	3.332%	$244.7315	$244.73	$244.75	$244.70
Purchase #7	$234.73	4.561%	$245.436	$245.44	$245.45	$245.40
7 purchase totals =	$1,095.99		$1,172.2674	$1,172.27	$1,172.30	$1,172.10