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	$201.73	10.327%	$222.5627	$222.56	$222.55	$222.60
Purchase #2	$118.98	4.497%	$124.3305	$124.33	$124.35	$124.30
Purchase #3	$59.28	3.823%	$61.5463	$61.55	$61.55	$61.50
Purchase #4	$182.68	4.402%	$190.7216	$190.72	$190.70	$190.70
Purchase #5	$148.68	11.127%	$165.2236	$165.22	$165.20	$165.20
Purchase #6	$200.65	12.830%	$226.3934	$226.39	$226.40	$226.40
Purchase #7	$28.31	13.524%	$32.1386	$32.14	$32.15	$32.10
7 purchase totals =	$940.31		$1,022.9167	$1,022.91	$1,022.90	$1,022.80