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	$167.90	13.620%	$190.768	$190.77	$190.75	$190.80
Purchase #2	$28.49	8.527%	$30.9193	$30.92	$30.90	$30.90
Purchase #3	$154.86	7.844%	$167.0072	$167.01	$167.00	$167.00
Purchase #4	$90.98	13.279%	$103.0612	$103.06	$103.05	$103.10
Purchase #5	$123.77	13.559%	$140.552	$140.55	$140.55	$140.60
Purchase #6	$244.96	3.352%	$253.1711	$253.17	$253.15	$253.20
Purchase #7	$187.26	11.281%	$208.3848	$208.38	$208.40	$208.40
7 purchase totals =	$998.22		$1,093.8636	$1,093.86	$1,093.80	$1,094.00