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	$178.28	10.155%	$196.3843	$196.38	$196.40	$196.40
Purchase #2	$64.66	10.740%	$71.6045	$71.60	$71.60	$71.60
Purchase #3	$246.52	9.247%	$269.3157	$269.32	$269.30	$269.30
Purchase #4	$96.51	13.576%	$109.6122	$109.61	$109.60	$109.60
Purchase #5	$85.76	8.419%	$92.9801	$92.98	$93.00	$93.00
Purchase #6	$108.38	13.617%	$123.1381	$123.14	$123.15	$123.10
Purchase #7	$168.93	9.204%	$184.4783	$184.48	$184.50	$184.50
7 purchase totals =	$949.04		$1,047.5132	$1,047.51	$1,047.55	$1,047.50