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	$223.47	13.661%	$253.9982	$254.00	$254.00	$254.00
Purchase #2	$47.82	5.182%	$50.298	$50.30	$50.30	$50.30
Purchase #3	$238.42	10.802%	$264.1741	$264.17	$264.15	$264.20
Purchase #4	$202.61	11.456%	$225.821	$225.82	$225.80	$225.80
Purchase #5	$217.72	10.681%	$240.9747	$240.97	$240.95	$241.00
Purchase #6	$94.82	6.332%	$100.824	$100.82	$100.80	$100.80
Purchase #7	$84.84	7.441%	$91.1529	$91.15	$91.15	$91.20
7 purchase totals =	$1,109.70		$1,227.2429	$1,227.23	$1,227.15	$1,227.30